\f REES£ LIBRARY
OP J
^UNIVERSITY OF CALIFORNIA.
THE PRACTICAL
METAL-WORKER'S ASSISTANT:
COMPRISING
METALLTTRGIC CHEMISTRY, THE ARTS OF WORKING ALL METALS AND ALLOYS, FORGING OP
IKON AND STEEL, HARDENING AND TEMPERING, MELTING AND MIXING, CASTING AND
FOUNDING, WORKS IN SHEET METAL, THE PROCESSES DEPENDENT ON THE
DUCTILITY OP THE METALS, SOLDERING, AND THE MOST IMPROVED
PROCESSES, AND TOOLS EMPLOYED BY METAL-WORKERS.
WITH THE
APPLICATION OF THE ART OF ELECTRO-METALLURGY
TO
MANUFACTURING PROCESSES:
COLLECTED FROM
ORIGINAL SOURCES, AND FROM THE WORKS OP HOLTZAPFFEL, BERGERON, LEUPOLD,
PLUMIER, NAPIER, SCOFFERN, CLAY, FAIRBAIRN, AND OTHERS.
BY
OLIVEK BTEKE.
A NEW, REVISED, AND IMPROVED EDITION.
TO WHICH IS ADDED
CONTAINING
THE MANUFACTURE OF RUSSIAN SHEET IRON.
BY JOHN PERCY, M.D., F.R.S.
THE MANUFACTURE OF MALLEABLE IRON CASTINGS, AND
IMPROVEMENTS IN BESSEMER STEEL.
BY A. A. FESQUET, CHEMIST AND ENGINEER.
With Six Hundred (ufar Ni\eijAig\cL}i\asf ihusff^tir^f every Branch of the Subject.
UNIVERSITY OF
('-AMI OUNLV.,
PHILADELPHIA:
HENKY CAREY BAIKD,
INDUSTRIAL PUBLISHER,
406 WALNUT STREET.
1874.
y
Entered according to Act of Congress, in the year 1864, by
HENRY CAREY BAIRD,
In the Office of the Clerk of the District Court in and for the Eastern District
of Pennsylvania.
STEREOTYPED BY 8. A. GEORGE,
607 BAS30M STREET, PHILADELPHIA.
COLLINS, PRINTER.
PREFACE.
THE PRACTICAL METAL-WORKER'S ASSISTANT, as now pre-
sented to the public, possesses some very valuable and essential
features not found in former editions, and which, it is believed,
will render it even more useful in the future than it has been
in the past, great as has been its popularity.
Dr. Percy's treatise on the Manufacture of Eussian Sheet-
Iron and Professor Fesquet's treatises on the Manufacture of
Malleable Iron Castings and Improvements in the Manufacture
of Bessemer Steel, are one and all important, especially in this
country, at the present moment, when a new era is opening
upon us, under the beneficent and wise policy which gives some
heed to our industries, and is producing such magnificent
results. Under this policy, as is most evident, the various
departments of the Iron and Steel manufacture are advancing
with rapid strides towards such a position as, it is believed,
must within two decades, if not sooner, place them at the head
of those industries throughout the world. Not only in these,
but in all of the other branches of metal working, must this
volume prove an important aid to the practical workman.
PHILADELPHIA, March 1, 1872.
(i)
CONTENTS.
CHAPTER I.
ON METALLURGIO CHEMISTRY.
The useful metals and metallic ores
defined 17
History of metallurgy. 19
Refining processes 22
New refining processes 23
Advantages of cast-iron 25
Crystallizing tendency of wrought-
iron in large masses 26
Classification of metals 27
Alloys 28
Affinity of metals 29
Theory of alloys 30
Metallic oxides 31
Reduction of metallic oxides 32
C arburetted hydrogen 33
Sulphides 34
Chlorides -. 35
Calcination and roasting 36
Carburets and carbons 37
Metallic salts ; 38
CHAPTER IT.
SPECIAL METALLURGIC OPERATIONS.
Volatile combinations 39
Metallic distillation processes.... 39
Fluxes and Fluxing 42
Furnaces 44
The combustive function 45
Products of combustion 47
Natural and artificial blasts 50
Blast machines 52
Catalan trompe 54
Chain blast 55
The Cagniardelle 56
CHAPTER TIT.
RECENTLY -PATENTED REFINING PRO-
CESSES.
Plant's process 57
Martien's process 58
Clay's process 59
Bessemer's process 60
Bessemer's converting vessel 62
Application of the tuyeres 64
Pouring out the fluid metal 65
Preparing the vessel 66
Process of conversion explained.. 67
Bessemer's squeezers 69
Bessemer's hammer and guage 70
Analysis of Bessemer's iron 71
Analysis of ordinary puddle-iron. 72
Reflections on Bessemer's process 73
CHAPTER IY.
REFINING AND WORKING OF IRON.
Iron-furnaces in the United States 75
Dickerson's method of making
wrought-iron directly from the
ore 75
Manufacture of malleable iron .... 77
Puddling... 77
Winslow's machine for compress-
ing puddlers' balls 77
Rollers or rolls of the iron works 80
Angle or T iron 81
Varieties of iron 82
CHAPTER V.
MANUFACTURE OF STEEL.
Cementation 83
Blistered steel 84
Shear steel 84
Cast-steel 84
Characteristics and qualities of
steel 85
Works on iron and steel 86
CHAPTER VI.
FORGING IRON AND STEEL.
Management of fires 86
The blast 88
Furnaces.' forges and hearths 88
Hand-forging 88
Anchors 88
Tongs and general tools 90
Oliver or small lift-hammer 92
Management of fires — the degrees
of heat 94
Ordinary practice of forging 97
Drawing down, jumping, building
up or welding 97
Set-hammers, flatters, top-fullers. 98
Twisting the work 98
Practice of hammering:. • 98
10
CONTEXTS.
Anvils 101
Methods in forging 101
Making bolts and nuts 103
Mortises 105
Levers, arms, brackets and frames 107
CHAPTER VII.
ON WROUGHT-IRON IN LARGE MASSES.
Forge tools
Limits of welding power
Auxiliary tools
Forge-hammers
Nasmytb's steam-hammer
Effects of Nasmyth's hammer....
Materials for forging
Tendency of over-refined iron to
deteriorate
Cast and wrought-iron for ord-
nance
Tensile strength of the monster-
gun
M aterial used in forging
Varieties of treatment required..
Modes of working large forgings.
Different modes of forging large
iron masses
Forging the monster gun
Crystallization explained
Crystalline tendency of iron
Causes of fissures and their remedy
Danger of forgings in cooling. . . .
Report of the Franklin Institute
on the " Princeton's" gun
Effects of hammer hardening....
Importance of metallurgy to en-
gineers
CHAPTER VIII.
GENERAL EXAMPLES OF WKLD1NG.
Shutting together, shuttin'g up.... 131
Welding heavy works 133
The butt joint 133
To form a T joint *. 133
Conical sockets, wrought-iron
hinges 134
Musket- barrels w . . . 134
Damascus-twist, stub-twist and
wire-twist . 135
Wrought-iron tubes 136
Chains 136
( 'hain-cables 137
Tires of wrought-iron wheels for
locomotives 137
Hatchets 138
S pades 139
Concluding remarks on forging ;
and the applications of heading
tools, swage tools, punches, etc. 140
108
109
110
111
112
113
114
115
116
117
119
120
120
121
122
123
125
127
128
128
130
131
Heading tools* 140
Swage tools 3 11
Trip and tilt-hammers, manufac
tured at the Lowell machine-
shop 143
CHAPTER IX.
HARDENING AND TEMPERING.
General view of the subject 1 44
Hammer hardening 145
The quantity of carbon in cast-
iron 145
Steel and glass polarized 14G
Practice of hardening and tem-
pering steel 147
Common examples of hardening
and tempering steel 153
Razors, penknives, hatchets, adzes,
cold chisels 154
Saws and springs 155
Less common examples of harden-
ing and precautionary measures 158*
Jacob Perkins's discovery 158
Oldham's process 159
CHAPTER X.
HARDENING CAST AND WROUGHT-IRON.
Chilled iron castings 103
Malleable iron castings 164
Case-hardening wrought and cast-
iron 164
CHAPTER XI.
ON THE APPLICATION OF IRON TO SHIP-
BUILDING.
Earliest use of iron in canal-boat
and ship-building 167
Variation of the compass in iron-
vessels rectified 168
Construction of iron vessels for
ocean traffic 169
Half cross section of a frigate. . . 170
Ribs 170
Keels 171
Decks 171
Form of the deck-beams 171
Riveting of the plates 172
Single and double riveted lap-
joints 173
Wood and iron as materials for
ship-building 175
Resistance to tension and com-
pression in iron-ships 175
Practical tests of iron-ships 176
Durability 178
Economy 178
Effects of shot on iron-ships 119
CONTENTS.
CHAPTER XII.
THE METALS AND ALLOYS MOST COM-
MONLY USED.
Description of the physical cha-
racter and uses of the metals
and alloys ^commonly employed
in the mechanical and useful
arts 180
Antimony 180
Bismuth 181
Copper 181
Alloys of copper and zinc only... 183
Remarks on the alloys of copper
and zinc 184
Alloys of copper and tin only. ... 185
Remarks on the alloys of copper
and tin only 186
Alloys of copper and lead only. . 186
Remarks on the alloys of copper
and lead only 187
Alloys of copper, zinc, tin and lead 187
Remarks on alloys of copper, zinc,
tin and lead 188
Gold alloys 190
Nickel 195
Palladium 195
Platinum 196
Rhodium 198
Silver 198
Silver alloys 199
Tin 200
Zinc 201
Babbitt's anti-attrition metal. ... 203
Fenton's anti-friction metal 203
Alloy of the standard measure
used by government 203
Tutenage 203
Expansion metal 203
Tables of the cohesive force of
solid bodies 204
Tabular view of some of the prop-
erties of metals 207
Weights of wrought-iron, steel,
copper and brass wire and plates 209
CHAPTER XIII.
REMARKS ON THE CHARACTER OF THE
METALS AND ALLOYS.
Hardness, fracture and color of
alloys 210
Malleability and ductility of alloys 212
Strength or cohesion of alloys.... 214
Alloy-balance 214
Table for converting decimal pro-
portions into divisions of the
pound avoirdupois 216
Fusibility of alloys 217
M. Mallett's process for the pro-
tection of iron from oxidation.. 217
Palladiumizing process 218
CHAPTER XIV.
MELTING AND MIXING THE METAI^.
The various furnaces, etc,, for
melting the metals 220
Antimony, copper, gold and silver
and their alloys 221
Observations on the management of
the furnace, and on mixing alloys 222
Britannia rnetal 224
Barren's furnace 229
CHAPTER XT.
CASTING AND FOUNDING.
Metallic moulds 230
Earthen moulds 230
Complex moulds 231
Metal moulds for pewter works... 232
Bearings for locomotive-engines.. . 233
Type founding., .-%-.- 235
Plaster of Paris moulds and sand
moulds 236
Stereotype founding , . 237
Moulding sand and flasks 237
Patterns, moulds and moulded
simple objects 238
Foundry patterns. 239
Cores of moulds 241
Moulding cored works 245
Core-boxes 246
False core and drawback 248
Reversing and figure-casting 249
Casting figures, ornaments,
branches and foliage... 250
Filling the moulds 252
Gun metal and pot metal 253
Iron-founders' flasks and sand-
moulds 254
Remarks on patterns for iron-
castings 261
Loam moulding 264
Melting and pouring iron 269
New method of manufacturing
drop shot 276
CHAPTER XVI.
WORKS IN SHEET METAL MADE BY JOIN-
ING.
On malleability, etc. — division of
the subject 278
Terrestrial globes 281
Works in sheet metal made by
cutting, bending and joining... . 281
A hexagonal box 28L
Polygonal figures of all kinds .... 282
Prismatic vessels 282
Pyramids 282
Frustums of pyramids 282
12
CONTENTS.
Mixed polygonal figures 283
Radiating pieces for polygonal
vases 284
Polygonal vases of unequal sides. 285
Tools for working in sheet met-
als 286
Modes of bending curved work... 288
Improved machine for rolling up
sheet-metal pipe 291
Angle and surface joints 292
Francis's metallic life-boats 295
CHAPTER XVII.
WORKS IN SHEET METAL, MADE BY RAIS-
ING J AND THE FLATTENING OF THIN
PLATES OF METAL.
Circular works spun in the lathe.. 300
Works raised by the hammer. . . . 303
Solid and hollow blows 304
Raising and hollowing 306
Raising globes 307
Vases 310
Jelly moulds 311
Stamping 312
Peculiarities in the tools and
methods 313
Principle and practice of flatten-
ing thin plates of metals with
the hammer 316
CHAPTER XVIII.
. PROCESSES DEPENDENT ON DUCTILITY.
Drawing wires, etc 322
Drawing metal tubes 327
Hydraulic press and arrangement
for manufacturing lead-pipe .... 330
CHAPTER XIX.
SOLDERING.
General remarks and tabular view 332
Tabular view of the process of
soldering 332
Hard soldering 333
Soft soldering 333
Soldering per se, or burning to-
gether 334
Alloys and their melting heats... 334
Fluxes 334
Modes of applying heat 334
Modes of applying heat in solder-
ing 335
The use of the blow-pipe 337
The workshop blow-pipe 338
Examples of hard soldering 339
Examples of soft soldering 341
Richemont'a airo-hydrogen blow-
pipe 350
CHAPTER XX.
SHEARS.
Cutting nippers for wire ':J52
Scissors and shears for soft flexi-
ble materials 354
Shears for metal worked by man-
ual power 360
Engineers' shearing tools, gener-
ally worked by steam-power. . . . 304
CHAPTER XXI.
PUNCHES.
Punches used without guides. ... 370
Punches used with simple guides. 874
Punches used in fly-presses, and
miscellaneous examples of their
products 377
Punching machinery used by en-
gineers 388
CHAPTER XXII.
DRILLS.
Drills for metal, used by hand 392
OTool's pin-drill 396
Methods of working drills by hand-
power 397
Drill stocks 399
Pump-drill 400
Press-drill 400
Expanding braces and lever-drill. 403
Ratchet-drill 403
Differential screw-drill 40")
Drilling and boring machine 405
Broaches for making taper-holes.. 413
CHAPTER XXIII.
SCREW-CUTTING TOOLS.
Originating screw 41 8
Cutting internal screw with taps. 420
The principle of chamfering 423
Transverse sections of taps 423
Die stocks 428
Master-taps 431
Bolt-screwing machine 437
Shaping machine 439
Screws cut by hand in a common
lathe 439
Cutting screws in lathes with tra-
versing mandrels 440
Cutting screws in lathes with tra-
versing tools 442
Healey's screw-cutting appara-
tus 445
System of change-wheels for screw
cutting 446
Screw-tools for angular threads... 453
Screw-tools for square threads 453
CONTENTS.
18
"Various modes of originating and
improving screws 457
Fusee engine 459
Kamsden's screw-cutting engine... 462
Clement's mode of originating the
screw-guide 466
Chucking and reaming lathe 469
Engine-lathe ~. 470
Screw-threads considered in re-
spect to their proportions, forces
and general characters 470
The measures and relative
strengths of screws 472
Sections derived from the angular
thread 480
Sections derived from square
threads 480
Table for angular thread-screws... 483
Table for small screws of fine an-
gular tl reads 484
Approximate values of Holtzapf-
fel's original screw-threads 485
Holtzapffel's original taps 487
CHAPTER XXIY.
HISTORY OF THE ART OF ELECTRO-METAL-
LURGY.
Yolta's discovery 489
Chemical decompositions by the
pile 490
First battery. 490
Decomposition by the battery, and
its application 490
Deposition of metals upon others. 491
Gilding 491
Early opinions concerning electro-
decomposition 491
How these results afifect the dis-
covery 492
Use of observed facts 493
Spencer's first experiments 493
Jacobi's experiments 493
Jordan's experiments 494
Spencer's first printed paper upon
electrotype 495
Historical anomaly 496
Plumbago as a coating 505
Separate battery 505
Laws of deposition 506
Works published on electro-metal-
lurgy 508
Patents taken out for electro-met-
allurgy 508
CHAPTER XX Y.
DESCRIPTION OF GALVANIC BATTERIES,
AND THEIR RESPECTIVE PECULIARITIES.
Nomenclature 509
Proposed terms 509
Batteries 510
Single pair of plates 510
Best kind of zinc 511
Amalgamation of the zinc
plates 511
Economy in amalgamation 512
Distance between the battery
plates 513
Different elements of batteries.... 513
Properties of metals fit for bat-
teries 515
Babington's battery 517
Wollaston's battery 518
Modification of Wollaston's bat-
tery now in use 518
Defects of common acid batteries. .519
Daniell's battery 522
Grove's battery 524
Bunsen's battery 526
Smee's battery 527
Earth battery 529
Magneto-electric machine 530
CHAPTER XXYI.
ELECTROTYPE PROCESSES.
Single-cell operations 533
Preparation of the coin 534
Forms of apparatus 535
Comparative view of exciting solu-
tions 536
How often solutions should be
changed, and zinc amalgamated 537
Making of moulds 538
Preparation of wax 539
To take moulds in wax 539
Rosin with wax 539
Moulds in plaster 539
Moulds in fusible alloy 540
Moulds in gutta-percha 541
Moulds from ferns, sea-weeds, etc. 541
Nature printing 542
Casting of reptiles, etc 542
Wax moulds from plaster 543
Mould of plaster from plaster
models 543
Fusible alloy from plaster 544
Copper moulds from plaster 544
Elastic moulding 544
Moulding of figures 545
Figures covered with copper 545
The preparation of non-metallic
moulds to receive deposit 545
Using metal moulds 547
Precautions on putting moulds
into a solution 54 «
Deposit on large objects 547
To make busts and figures 548
Coating of flowers, etc 548
Figures from elastic moulds 549
14
CONTEXTS.
Electrotypes from daguerreotypes. 550
Depositing by separate battery.... 550
Size of the electrodes 552
Relative power of batteries 552
Constancy of batteries 552
Comparative power of batteries.. 553
Recovery of mercury from waste
zinc 556
Compound cell process 556
Effects of resistance 557
I ntensity 558
Relative intensity of batteries.... 559
Mode of suspending objects in
coating 560
Non-transfer of elements 561
Effects of difference in the density
of solutions 562
Crystals of copper on electrodes.. 562
CHAPTER XXVII.
MISCELLANEOUS APPLICATIONS OF THE
PROCESS OF COATING WITH COPPER.
Coppered cloth 563
Calico-printers' rollers 564
Etching of rollers 564
Printing 564
Glyphography 564
Instruction on Glyphography for
the amateur 566
Copying of copper-plate engrav-
vings 568
Coating of glass and porcelain 568
On galvanic soldering 569
Graham plastic niello 571
CHAPTER XXVIII.
BRONZING.
Brown bronzes 573
Another method 573
Black bronzes 573
Green bronzes 574
CHAPTER XXIX.
DEPOSITIONS OF METALS UPON ONE AN-
OTHER.
Coating of iron with copper 574
Cyanide of potassium 575
Cyanide of copper 577
Peculiarities in working cyanide
of copper solution 578
Preparation of iron for coating
with copper 579
Effects of conducting power in
solutions and metals 579
Illustration of conduction 580
Non-adherence of deposit 581
Coating cast-iron with other met-
als 581
Coating of iron with zinc 583
Sulphate of zinc 583
Use of zinc coating 594
Influence of galvanism in protect-
ing metals from destruction by
oxidation and solution 585
CHAPTER XXX.
ELECTRO-PLATING.
To make silver solution 587
Cyanide of silver dissolved in yel-
low prussiate of potash 588
Solution made with oxide of silver 588
Solution made with chloride of
silver 589
The best method of making silver
solutions 589
Hyposulphite of silver solution... 590
Sulphite of silver-plating solution 591
To recover silver from solution.... 592
Preparation of articles for plating 593
Practical instructions in plating... 594
Taking silver from copper, etc 597
Cyanide of silver and potassium —
decomposition during the plat-
ing process 597
Other effects produced in working 598
Machine for moving goods while
subjecting to the electro-plating
process 598
Opposite currents of electricity
from vats 600
Tests for the quantity of free cya-
nide of potassium in solutions.. 601
Rate of depositing silver 603
Bright deposit 603
Different metals for plating 603
Electricity given off from sandy
deposits 604
The old method of plating 604
Advantages of electro-plating. . . . 605
Objections to electro-plating 606
Solid silver articles made by the
battery 607
Dead silvering for medals 609
Oxidizing silver (i()9
Protection of silver surface 609
Cleaning of silver 610
CHAPTER XXXI.
ELECTRO-GILDING.
Preparation of solution of gold... 610
Battery process of preparing gold
solution 611
Process of gilding 612
Conditions required in gilding. . . . 612
Maintaining the gold solution .... 613
To regulate the color of the gild-
ing 614
CONTENTS.
15
Coloring of gilding 614
To dissolve gold from gilt articles 614
To recover the gold 615
Objections to electro-gilding 615
Effects of cyanogen on health. . . . 615
Practical suggestions in gilding.. 617
Deposition of bronze 617
CHAPTER XXXII.
RESULTS OF EXPERIMENTS ON THE DEPOSI-
TION ON OTHER METALS AS COATINGS.
Coating with platinum 617
Coating with palladium 618
Coating with nickel 618
Antimony, arsenic, tin, iron, lead,
bismuth and cadmium 619
Iron 619
Lead 619
Aluminium and silicium 619
Tin 622
Antim ony 622
Deposition of alloys 622
CHAPTER XXXIII.
THEORETICAL OBSERVATIONS.
Action of sulphate of copper on
iron 628
Faraday's theory of electrolysis... 628
Graham's theory of electrolysis... 629
Daniell's and M iller's views 630
Proposed theory 631
APPENDIX.
MANUFACTURE OF RUSSIAN SHEET-IRON.
Qualities of Russian sheet-iron 633
Chemical examination 633
Secret manufacture 634
Sources of information 634
Description of the mode of manufac-
ture, by Mr. Septimus Beardmore 635
Description of the mode of manufac-
ture, by Prof. Pumpelly 636
Dinas bricks 637
Description of the mode of manufac-
ture, by Herbert Barry 637
Michailovskoi works 638
lakovleff sheet-iron 639
Description of the mode of manufac-
ture, communicated to the author
by N. De Khanikof. 639
Description of the mode of manufac-
ture, by Captain N. Meshtcherin. 641
Hammers and anvil 642
Re-heating furnace 643
Puddled bar and resulting sheets... 644
Manner of strewing the charcoal
powder 645
Packets of sheets 645
Rack in which the second-hammered
sheets are arranged 646
AMERICAN SHEET-IRON.
Imitation of Russian sheet-iron 649
MALLEABLE IRON CASTINGS.
What is meant by malleable iron
castings 651
States in which carbon exists in
cast-iron 651
Removal of carbon from cast-iron... 652
Reaumer's book on the "Art of con-
verting wrought-iron into steel,
and softening cast-iron," published
in 1722 653
Malleable iron works of Messrs.
Carr, Crawley & Devlin, Philadel-
phia, with the apparatus and pro-
cesses there in use 654
Pig-iron used 654
Cupolas and reverberatory furnace.. 654
Sand and patterns in casting 655
"Tumblers" 655
Packing of the casting in cast-iron
boxes and arrangement in the an-
nealing furnace 655
Annealing furnace 655
Subjecting to heat 655
Coveringwith oxide 656
Removal of adherent oxide and
finishing 656
Sal ammoniac for rusting the scales 656
Products of this factory 656
Cost of malleable iron castings 656
Use of malleable castings 656
Oxide of zinc 656
BESSEMER STEEL. — IMPROVEMENTS IN
THE PROCESS.
Pig-metal required 657
Doctoring 657
Cumberland pig 657
Decarburizing and recarburizing the
metal 657
Use of Spiegeleisen 657
Apparatus 658
The converter 659
The blast 659
Mode of operation 659
Classification of steel as used at the
Belgian works of Seraing, near .
Liege 660
INDEX .. 663
THE PRACTICAL
METAL-WORKER'S ASSISTANT.
CHAPTER I.
ON METALLURGIC CHEMISTRY.
THE USEFUL METALS AND METALLIC ORES DEFINED. — Of sixty-
four simple or elementary material bodies, no less than fifty or
fifty-one are metallic. We shall not enter upon the characteristics
which serve to define a metal — that more especially belongs to the
functions of a chemical treatise ; but taking it for granted that the
attributes of a metal are sufficiently well agreed upon for popular
use, we shall proceed to offer a few general remarks on their useful
properties, of which rigidity, cohesion, tenacity, and durability are
the most remarkable, although many more are conjoined in varia-
ble degrees.
The ancients were only acquainted with seven metals, whereas
we know of fifty or fifty-one ; nevertheless those now in most
general requisition, and to which the appellation "useful metals"
most peculiarly belongs, were all known to the ancients. Methods
of working them, however, and new sources from which to obtain
them, have multiplied so much in modern times as almost to rank
in importance with the discovery of the existence of a new metal.
Metals are either found native — that is to say, in the condition
of obvious metallic existence — or they are combined with other
substances, so as to lose all obvious evidence of their metallic con-
stitution. The latter condition is by far the more frequent ; and
to this fact more than any other the consecutive history of special
metallic discovery is attributable. This circumstance leads us to
an important chemical consideration, having reference to the com-
parative tendencies of different metals to combine with- the non-
metallic elements, and to lose by such combination their obvious
metallic form. The term " noble metals," though applied to gold
and silver in ages when the principles of chemical science were un-
known, has nevertheless a positive chemical significance. Modern
discovery has added platinum to the list ; and they all agree in
2 17
18 THE PRACTICAL METAL-WOEKDB'a ASSISTANT.
the property of being very slow to combine with any foreign
material save other metals. Hence it is that they are so frequently
found (gold and platinum almost universally) in the native or
metallic state, united frequently with other metals, it is true, but
still exhibiting the metallic aspect. If the noble metals existed in
larger quantity, offered equal facility for working them, and equal
hardness after being worked, their slowness to unite with oxygen
would render them, more than all others, deserving of the appella-
tion of " useful metals ;" but, being deficient in these qualities,
notwithstanding their nobility, they must yield the palm to iron,
tin, copper, zinc, and lead, in the first instance, and perhaps to
mercury or quicksilver, and bismuth also ; considering the various
applications of these metals to the useful arts of life.
The progress of metallurgy and of smelting operations demon-
strates how great may be the advance of arts based upon scientific
principles, without these principles being understood. The pro-
duction and utilization of metals are intimately allied with
chemistry; and deriving such immense advantages from the appli-
cation of chemical principles at this time, it is extraordinary to
reflect on the comparative excellence to which the art of working
several useful metals had arrived, before the aggregation of
chemical facts and principles to which the denomination " science"
is alone justly due, had dawned. Chemical science may be indeed
said to rest on an historical basis of metallurgic aspirations, and
metallurgic empiricism.
Coeval with the earliest historical records, some metals were
worked, and the operations of working involved the influence of
chemical laws ; yet the simplest principles of chemistry had not
then dawned. At later periods it was alchemy — the vague hallu-
cination of making gold — which prompted men to undertake
investigations fruitful of chemical deductions, to be marshalled
into a science hereafter. Metallurgy, then, may justly lay claim
to be considered the fountain source of chemistry ; and the subse-
quent development of the science to the art, might supply the
theme of argument in favor of empiricism over intellectualism, if,
at various periods within the last two hundred years, the miner
and the metallurgist, by their devotion to chemistry, and the
chemist by his successful labors in the practical fields of mining
and smelting, had not demonstrated how mutual is the relation
between theory and practice, how inseparable for good, how
redundant of advantages the one to the other. Metallurgy (accept-
ing the word in its most extensive signification) derives its best
processes, and not unfrequently its best practical aids, from a due
appreciation of chemical principles. And, on the other hand, the
mere theoretical chemist derives a useful lesson of the necessity of
checking his theoretical deductions by facts, as they are found to
be, by attending to some of the teachings of metallurgy. Several
metallic operations there are, the success of which is at variance
with all the theoretical indications of chemistry v "Corpora non
ON" METALLURGIC CHEMISTRY. 19
agunt nisi fluida" was a chemical dictum of received universality ;
nevertheless, the practice of annealing, or the conversion of iron
into steel by combination with carbon, is a practical refutation of
the universality. This process consists in the heating together
iron bars and wood-charcoal in a suitable furnace. Both iron and
carbon are here brought together in the solid state ; both may be
said to be devoid of volatility, and almost of liquidity ; neverthe-
less, in violation of the formerly received canon, combination
ensues, and steel is made. A similar disaecordance between the
indications of theory, and the teachings of practice,. is illustrated
by the hot-blast operation, introduced some years ago in the
practice of iron smelting. On the other hand, chemistry illumi-
nates many dark recesses in the field of metallic empiricism, and
points to facts, the existence of which would not have been sus-
pected.
It is unnecessary, however, further to expatiate on the advan-
tages which the metal-worker derives from, the knowledge and
application of chemical theory, the connection being now admitted
by none more readily than by the practical metallurgist.
HISTORY or METALLURGY. — In illustration of the mutual
dependences of a branch of practical metallurgy and chemical
science, it may be here not unadvisable to anticipate the contents
of the monographs which especially deal with special metals, and
to trace cursorily the various phases which the production of the
metal iron has undergone. From one of several metalliferous
sources this useful body has been produced from perhaps the
earliest historical periods. True though it be th#t the ancient
Greeks, at the very earliest period of their history, do not seem to
have been acquainted with the existence of, far less the method of
working, iron — yet we read of both in Scripture; and there is
good reason to believe that anterior to the earliest historical record
of the Greeks, iron, and the processes of manufacturing it, were
known in, China and Hindostan. We know, too, that immutability
is impressed on all the processes of the East; whence it is not un-
reasonable to infer that the processes of rude iron manufacture now
followed in Asia, are types of, if not identical with the processes
followed there in times long passed. What are these processes ?
What is their general characteristic ? What are the principles in-
volved ? What is the result ? One general scheme of appliances
pervades them all. The object is to begin with an ore of iron
capable of reduction by charcoal fuel, and of yielding a semi-fluid
result, which the subsequent process of welding fashions into shape.
Even in this simple form of iron-smelting, a good deal of latent
chemistry is involved ; but the fullest acquaintance with chemistry
could not improve the practice of iron-smelting, as followed by the
Persians and Hindoos, if limited to the means at their command,
and the ends proposed to be gained. The iron manufacture of
England, as prosecuted in bloomaries by the aid of charcoal fuel
was only a modification of the Persian method, and conducted
20 THE PRACTICAL METAL-WORKER'S ASSISTANT.
almost as empirically. No sooner was the practice of iron-smelt
ing by charcoal fuel abolished, and pit-coal, or its immediate
derivative coke, introduced, then an application of chemical
principles became necessary. How far these applications resulted
in empirical tentative experiments, or in the suggestions of chemi-
cal teaching, it would not be possible at this time to decide ; but
the historian of the iron manufacture- has not to pursue his labors
much further before the reaction of chemical knowledge on mere
empiricism is made evident. Practice demonstrated the fact that
coal-smelted iron was inferior to charcoal-smelted iron; but
practice could not say wherefore, until science came to the iron-
smelter^ aid, making known to him the composition of pit-coal,
proving that it contained many foreign substances, which found
their way into the smelted iron, and injured its quality. Analysis
of coal-smelted iron demonstrated the existence of both sulphur
and phosphorus incorporated with it, demonstrated moreover that,
coeteris jwribus, the amount of deterioration of the iron was in
direct proportion to the quantity of these elements which it con-
tained.
Chemistry next began to shed a light on the nature and property
of fluxes, in showing how a mixture of several iron ores might
conduce to yield a more fluid mass in the furnace than any one ore
by itself. The next chemical glimmering fell on the apprehension
of Cort, that Nestor of the British iron trade, and led to his im-
provements in the processes of refining and puddling, the results
of which, combined with the rolling aid devised by his mechanical
genius, eventuated in Britain, supplying iron in large quantities
to other countries, from which she had heretofore obtained that
metal.
It was our proposition, that as the operations of metallurgy
(accepting the word in its largest sense) came down to our own
times, the reaction of theoretical chemistry upon its practical
development has continued to increase. Whilst the supply of
British wood-charcoal lasted, and before the demand for iron
became so enormous, as it has from the beginning of the last
century, charcoal answered its purpose tolerably well. The iron
manufactured by it resulted in small quantity ; but, by comparison
with coal, or coke-smelted iron, it was pure. England, however,
in course of time became deforested in the neighborhood of the
existing iron -works, the source of wood-charcoal thus failed, and
pit-coal of necessity was obliged to be employed henceforth for the
production of iron. Simultaneously with its adoption, the clay
iron-stone began to supply the place, to a variable extent, with
iron ore. The result was attended with both advantages and
defects.
Iron admitted of being obtained in enormous quantities from
these sources ; but it had no longer the purity of the charcoal-iron
of heretofore. Not only was the quality of the result deteriorated
by the presence of impurities originally contained in the ore; but
ON METALLUEGIC CHEMISTRY. 21
other impurities, especially sulphur, derived their existence from
the coal or coke employed as fuel. Against the presence of these
impurities, iron manufacturers have continued, in one sense, to
struggle up to the present time. The difficulty of getting rid of
these impurities, however, has not been entirely disadvantageous.
The fact is known even, to general popularity, that the only differ-
ence between wrought-iron and cast-iron consists in the relation
between the extraneous bodies — chemically speaking, impurities —
in each, and the results -of mechanical action upon the former.
Iron absolutely or chemically pure, is far more rare, and more
difficult to obtain than absolutely pure gold. It is, indeed, only
met with in chemical laboratories, and very seldom there.
Wrought-iron, however, may be practically considered as pure
iron; and cast-iron as the latter combined with some four or five
per cent, of impurities. That such impurities are not prejudicial
to the nature of iron for all purposes and all uses, will be rendered
sufficiently evident by a consideration of the products made of
wrought and cast-iron respectively. Wrought-iron (that is to say,
commercially pure iron) is almost infusible. By virtue of its
malleability and power of adhesion under the operation of welding,
it may be fashioned into a multiplicity of useful formsj but if any
person casts his eye over the comparative number and variety of
the products of cast and wrought-iron respectively, and reflects on
the fusible quality which the presence of certain impurities confers,
he will rise from the survey with the conviction that the existence
of these impurities in iron, and the difficulties of evolving them,
are not without their advantages. To these circumstances we owe
the enormous development which the production and working into
shape of cast-iron has attained ; so that whilst we have been neces-
sarily dependent upon the purer charcoal iron of Sweden, Norway,
and Russia, as the basis of our steel and wrought-iron for exclusive
-purposes, cast-iron girders and bridge-beams made in this country
have been largely exported.
Nevertheless, it was desirable that we should not be restricted
to the operation of casting, but that we should be able to abstract
the four or five per cent, of impurities fro'm the cast material, and
thus change it into wrought-iron. All the consecutive improve-
ments in refining and puddling have had reference to this end ;
but, notwithstanding the comparative perfection to which these pro-
cesses have been brought by Cort, and others — notwithstanding the
mechanical aids of hammering and rolling, by which it was hoped
that such impurities as could not be rendered capable of entering
by combustion into volatile products would be mechanically
forced away — the problem has never been solved of abstracting the
impurities from cast-iron, and rendering the result equal in quality
to the charcoal wrought-irons imported from Russia, Norway, and
Sweden. All the chemical processes of iron purification hitherto
employed on the large scale had been based on the operation of
bringing highly -heated external surfaces of molten, or pasty iron
22 THE PRACTICAL METAL-WORKER'S ASSISTANT.
m contact with atmospheric air, and renewing the surface as
often as the impurities which studded it had been burned away.
The operations of refining and paddling were designed with this
object in view ; and the operations of mechanical extrusion effected
by hammering, or cylindrical pressure, were designed with the
object, and successfully carried out up to a certain point, of accom-
plishing by mechanical means that which chemistry alone was
unable to effect.
REFINING PROCESSES. — Every person who takes a passing
glance at the operations of metallurgy in the aggregate, cannot
fail to be struck with a certain functional similarity between the
process of cupellation as applied to separate ignoble from noble
metals, and the process of puddling, by virtue of which the im-
purities held by cast-iron are removed from the latter. In both
cases the general result is obtained by passing a current of air
over a highly-heated metallic surface. The puddling process (for
perfecting which the world was indebted to the ill-requited
Richard Cort) consists in placing partly-purified iron in a rever-
beratory furnace, and vigorously stirring it about so as to expose
it to the action of the air : by which operation oxygen is rapidly
absorbed, while carbonic acid gas escapes, giving the metal a
bubbling and boiling appearance. As carbon escapes, the metal
passes from a fluid to a spongy half-fluid mass ; and in this state it
is ready for the puddler. The metal is collected at the end of
an iron bar, in a ball or bloom of sufficient size, which is swung
through the air, and placed under the forge-hammer, to the crush-
ing blows of which it is subjected, being turned and twisted in
every possible direction, while sparks of fire dart from the surface,
and liquid drops exude from the interior of the metal.
This is continued until the ball rings under the hammer, and
the liquid drops give place to scaly masses. In this state it is
passed through the rollers, in the grooves of which it is drawn out
and compressed, then doubled up and rolled ; again heated, doubled
up and rolled, until the process is complete. The new process,
by which the reader will be at no loss to understand that we
advert to the scheme devised by Mr. Bessemer, advances by one
step further, as it is stated, and may be considered to be a nearer
approach to the complete purification. By it a current of atmos-
pheric air is forcibly projected not over but through a molten
mass of impure iron ; and it is assumed that by the chemical
operation of this atmospheric blast, such impurities as are at
once combustible, and the volatile results of combustion, will be
expelled.
Now the combustible extraneous matters are for the most part
carbon, sulphur, and phosphorus. The results of combustion of
the first, will evidently be carbonic acid and carbonic oxide, both
volatile; of the second, sulphurous acid, also volatile; of the third,
phosphoric acid, not volatile. The theory of the process is based
upon the idea of removing the impurities by the 'heat developed
OX METALLURGIC CHEMISTRY. 23
from their own combustion, instead of employing other combusti-
bles, themselves holding impurities.
A more beautiful and more immediate application of chemical
knowledge to improvement of the iron manufacture it is impossible
to conceive ; although from its recent occurrence, and the proba-
tionary stage to which it has only yet arrived, we are precluded
from treating of it without a certain feeling of constraint insepara-
ble from the dawn of all new inventions.
Our remarks have already conveyed sufficient intimation of our
cognizance that the indications of theory and the deductions of
practice are not always accordant to satisfy the reader of . our
freedom from any mere theoretical bias. At this early period,
however, Mr. Bessemer, in common with every inventor who lays
before the world a proposition which he believes in, and which a
large section of the public is prepared to receive as an improve-
ment on pre-existing modes, is probably experiencing some of the
crosses and disagreeables inseparable from the office of pioneer in
the regions of science or the arts. It is only a matter of common
justice, then, that those who have to speak or write of processes in
his domain, should give them, so far as in them lies, a helping
word of congratulation. Without, therefore, committing ourselves
to a premature expression as to how much or how little the pro-
cesses may accomplish, we are justified in stating that which is
much more satisfactory to him and to us. The communications
we have opened in relation to the matters in hand, have necessarily
thrown us into correspondence with various iron-smelters. On
the premises of one of these — one of the largest, if not the very
largest in Great Britain — Mr. Bessemer's process is about to be
placed on trial, and under the most favorable auspices for 8, search-
ing and impartial one ; the result of which will be communicated
to our readers in the present volume.
But it becomes a question of very grave import, and one
requiring the test of wear and tear of time as well as experiment,
to set at rest, whether there are not mechanical requirements in
preparing malleable iron not comprised in Mr. Bessemer's pro-
cess. Iron, like all other metals, has a strong tendency to crystallize
at a given temperature ; and an ingenious friend, theorizing on the
subject, suggests an hypothesis which we have not met with before,
that the puddling process supplies a mechanical as well as a
chemical bond of union in the metal. The crystals, he suggests,
are disturbed at the moment of formation, driven into each other
by the stirring operation ; and that the jagged edges of the particles
thus become knitted or laced into each other in a fibrous mass.
This would seem to explain the tenacious and fibrous character
of wrought-iron ; and if so, it may be doubted if the new process
will altogether supersede that of puddling, though it may greatly
facilitate the operation.
Nor does it appear that Mr. Bessemer will be suffered to mo-
nopolize the attention of those interested in iron. Mr. Plant, of
24
Holly Hall Colliery, Dudley, had patented, as early as July, 1849,
a refining process by which a current of air and steam is directed
upon the iron while it is in the puddling furnace. Another pro-
cess, patented in 1855, by Mr. Martien, of New Jersey, consists in
passing currents of air and steam through the heated cast-iron as it
runs from the blast furnace. A third invention is by Captain
Uchatius, Engineer-in-Chief of the Imperial Arsenal, Vienna, who
has devised a method of producing every description of cast-steel
from crude pig-iron in the short space of three hours ; and the
process was exhibited in London before a number of scientific and
practical men, to their entire satisfaction, as it is stated ; although
these experiments were conducted in furnaces not we'll suited to
the operation. This process consists of running melted pig-iron
from a crucible into a vessel filled with water, when the iron is
converted into small granulated shot-like particles. A weight of
twenty-four pounds of these granulated iron drops was mixed with
crushed ore and filled into a crucible, which was placed on the
furnace prepared for it. After the lapse of a period of two hours
and three-quarters, the crucible was taken from the furnace and the
contents poured into an iron mould. When this was opened, an
ingot of steel weighing twenty-five pounds was exhibited to the
company, and pronounced by competent judges to bear every ex-
ternal evidence of being perfect in quality. While this metal was
being melted, an ingot of steel prepared by this process at the steel
works of Messrs. Turton, of Sheffield, was subjected to the steam
hammer, and a bar of steel produced from the ingot which was
pronounced to be of excellent quality by the practical men present.
It is impossible to over-estimate the importance of these discoveries
should they bear the test of experiment on a suitable scale.
Between theoretical indication and practical confirmation, how-
ever, there is a bridge to be passed, which frequently breaks clown
and engulfs the inventor, through the interposition of some collat-
eral obstacle. It may be that the processes of Mr. Bessemer and
the other ingenious men named are in this category. Davy sug-
gested the protection of the copper bottoms of ships by the attach-
ment of zinc galvanic preservers. He caused the suggestion to
be practically carried out, and quoad protection it succeeded. But
Davy was foiled, and his process was rendered inoperative through
the interposition of a collateral circumstance which had not en-
tered into his calculations. The copper was no sooner prevented
from undergoing solution, than its surface became harmless ; sea-
weeds and sea-mollusks stuck to it, and the ship's course was im-
peded thereby. It may be somewhat thus with the inventions to
which we have adverted, — some collateral issue may interfere with
the practical realization of the inventor's hopes in respect of the
invention. It is always well to bear in mind these probabilities,
seeing that they are the reflex of the history of most inventions.
But nevertheless the theory on which Mr. Bessemer's operation is
based is so simply beautiful, that now, at this early stage of it, be-
ON METALLURGIC CHEMISTEY. 25
fore the ultimate practical issues of it are known, it is fitting that
Mr. Bessemer should be cheered with the provisional recognition
which a clear apprehension of principles, and a seemingly prac-
tical way of giving them effect, bespeak as justly his due. In the
puny microcosm of a chemical laboratory, where thousands of
little appliances can be invoked to gain the end proposed by chem-
ical analysis — it is possible, nay, it is probable, that a chemist may
not justly interpret the data which small operations evolve, into
the less numerous, though individually larger, conditions of the
practical man.
ADVANTAGES OF CAST-IRON. — "We have already intimated that
the presence of impurities in iron as rendered by our smelting
works, and the difficulties of removing them, are not barren of all
good results ; and we have adverted to the capabilities of cast-iron.
Let us now contemplate the subject of iron from the opposite point
of view ; let us assume that instead of the facility wherewith the
genius of our smelting operations enables us to turn out enormous
quantities of iron, cast into the form required, the genius of the
process had been in the direction of depriving us of this impure
material, but rendering us iron commercially pure — that is to say,
in the state of wrought iron. What difficulties would have beset
us then ! The operation of casting no longer possible, but every
piece of manufactured iron being necessarily manufactured by the
laborious operations of forging, hammering, and welding, — not
merely would the price of iron for many purposes have been en-
hanced, but for numerous purposes to which iron is now applied
it could not have been used at all. Contemplate the prices of cast-
iron which constitute the blocks of which Southwark Bridge is
built, and imagine the circumference of blocks having the same
form, weight, and dimensions, made of wrought instead of cast-
iron, and hammered into shape. The thing would have been utterly
impossible. It would be impossible even now, notwithstanding
the aid of the ponderous steam-hammer. The ease with which a
blacksmith heats, and welds, and fashions into shape the half-
molten paste of glowing wrought-iron on his anvil, would convey
but feeble indications of the difficulties which beset these opera-
tions when conducted on a large scale. It is difficult to pronounce,
and it would be invidious to make the attempt of fixing, the ex-
treme limits or size of which a piece of wrought-iron admits of
being forged. Practical effect is given to that operation to the
extent of forging anchors, shafts and beams, for the largest marine
engines. These are achievements sufficiently difficult, and until
lately critics were found — nay, indeed, they are to be found still —
who confidently assert that much beyond these achievements of
wrought-iron manufacture the operation could not go. Whether
wrought-iron ordnance of large size could or could not be manu-
factured, having the strength necessary to ordnance practice, was
a moot-point. Some years ago the experiment was tried in the
United States, and failed, — as a terrible accident from the bursting
26 THE PRACTICAL METAL-WORKER'S ASSISTANT.
of a wrought-iron piece of ordnance painfully testified. Since
then Mr. Nasmyth repeated the experiment, with so bad a result
that it was considered by himself to be a failure, and he expressed
himself very hopelessly respecting wrought-iron heavy ordnance.
Nevertheless, a large piece has been made by an enterprising Liv-
erpool firm, and presented to the British government. It is now,
whilst these remarks are written, under process of trial ; and
hitherto it bis stood all the tests deemed necessary with complete
satisfaction.
The result of the manufacture of this interesting piece of ord-
nance, and the trials to which it has been subjected, demonstrate
that those who ex cathedra predicted so confidently that wrought-
iron heavy ordnance could not be made (due regard being had to
their strength), may have reason to alter their opinions. Con-
fessedly, however, as between the casting of iron into a specific
shape, and the welding and hammering of iron into a similar shape,
the difference is enormous.
In addition to the mechanical difficulties attendant on the ma-
nipulation of wrought-iron — in addition to the difficulties of re-
moving huge masses of it from the forge to the anvil — the difficulty,
moreover, of welding two or more large pieces together in such a
manner as to give solidity to the welded joint — a chemical or
molecular tendency of wrought-iron when retained at a glowing
heat in large masses for long periods together, threatened to impose
an insuperable barrier to the manipulation of wrought-iron in
pieces much larger than anchors, or marine steam-engine axes.
CRYSTALLIZING TENDENCY OF WROUGHT-!RON IN LARGE
MASSES. — It was found by Mr. Nasmyth, in turning out his mon-
ster gun, that the iron had ceased to be fibrous, and had assumed
a crystalline texture at its centre, thus losing the strength and
tenacity which the fibrous condition would have given. It had
been fully known that wrought-iron under some peculiar circum-
stances is prone to assume this condition. The axles of revolving
carriage- wheels have been known to assume this crystalline state
from vibration, after the lapse of time and long usage, although they
were originally fabricated of the best wrought-iron. Iron wire
too, which, as all connected with metallurgy know, is necessarily
made of the purest iron, occasionally assumes this crystalline state
if long exposed to the agency of chemical forces ; as, for instance,
in a laboratory. Various hypotheses have been propounded to
afford a rational explanation of this molecular change from fibrous
to crystalline condition. As regards the case of railway axles, the
supposition appears rational that constant percussion has given rise
to the crystallized state ; but the change experienced by iron wire
is not so plausibly explicable. The crystallization of large masses
of wrought-iron under the heating and cooling process involved
in the operation of welding, seems to admit of easier explanation.
The result appears to be only a special illustration of a general
resultant of the undisturbed play of cohesive 'affinity, tending as
ON METALLURGIC CHEMISTRY. 27
it does, if sufficient time and freedom of molecular motion be given,
to assume the most perfect cohesive state of which matter is capa-
ble— that is to say, the state of crystals. Had the result of crys-
tallization been inseparable from the practice of welding large bars
of iron, there would have been an end to wrought-iron ordnance
of large calibre ; there would have been an end also to the pro-
duction of any pieces of wrought-iron considerably larger in
dimensions than the forms hitherto produced. We shall look
forward therefore with some interest to the monograph on the
working of wrought-iron in large masses promised us by Mr.
Clay.
Impressed with specialities as the metals are, each one conducing
to certain purposes better than any other — nevertheless, with the
exception of iron, these capabilities are numerous, and one gen-
erally admits of being substituted for another. But no civilized
race could exist as such without the co-operation of the metal iron.
For the greater number of purposes to which it is applied there is
no efficient substitute. True, the ancients did manage at one time
to manufacture cutting instruments out of bronze ; true, that Sir
Francis Chantrey in our own times, in his reverence for classic
metallurgy, caused a bronze razor to be made, wherewith he
shaved ; nevertheless, we doubt whether any one less ardent in the
love of ancient metallurgy than himself would have borne con-
tentedly the daily infliction.
CLASSIFICATION OF METALS. — Before indicating the chemical
principles upon which each special process of metallurgy is based,
it will be desirable to arrange the metals in classes, according to
the several characteristics which they present. Great specific
gravity is so prominent a characteristic of metallic bodies, viewed
in the aggregate, that anterior to the discovery of potassium, so-
dium, and the other alkaline and terrigenous metals, the quality
was thought to be inseparable from the metallic condition. So far,
however, is this from the truth, that lithium — the metal of the
alkali or alkaline earth lithia : it may be said to be intermediate
between the two — is the lightest known solid, metallic or non-
metallic, in all nature. Based on a consideration of the quality of
specific gravity, then, we arrive at a division of metallic bodies
into the light and the heavy. In a purely chemical senser such a
division has no value. But it is otherwise to the metallurgist.
Inasmuch as the metals of the alkalies and alkaline earths — that is
to say, the light metals — are only produced by complex and re-
fined chemical processes, they may be considered as lying without
the domains of metallurgy. It is only with the remaining class
(the heavy metals), therefore, that the metallurgist has to concern
himself, and to which the reader's attention throughout this intro-
duction and the succeeding pages will be exclusively directed.
Contemplating the heavy metallic bodies, in a practical or metal-
lurgic sense, with reference to their subdivision, their various
demeanor with regard to oxygen, and their general relations to
28 THE PRACTICAL METAL- WORKER'S ASSISTANT.
that extensively diffused non-metallic element, we have a natural
as well as a ready means of classification. It has been calculated
that almost two -thirds by weight of our globe's constituents —
solid, liquid, and gaseous ; its vegetables, and its animals and min-
erals— consist of oxygen. The chemist need not to be reminded
of the powerful tendency to combustion which oxygen manifests,
especially wiUi metals. Unquestionably the most considerable
and the most important metallic ores are oxides, or combinations
with oxygen. It is natural, therefore, that the metallurgist should
seek, in an examination of the relations of metals to oxygen, the
basis of their practical subdivision. Five well-marked subdi-
visions, founded on these peculiarities, admit of being established.
They are as follow :
1. Metals having a strong tendency to combine with oxygen, and
to generate bases. These metals admit of arrangement in three
sections.
§ (a). Metals whose oxygen-compounds are basic, or have the
property of bases. They are zinc, cadmium, lead, and uranium.
§ (b). This section has only one representative, i. e. arsenic, or
arsenicum ; a metal the peculiarity of which is, that its combina-
tions with oxygen are acid, not basic.
§ (c). Metals which form both acids and bases by combination
with oxygen. They comprehend copper, nickel, cobalt, bismuth,
tin, copper, manganese, iron, antimony.
2. Metals the tendency of which to combine with oxygen is but
slight : comprehending gold, silver, platinum, and mercury. The
three former are sometimes called " noble metals."
The relative fusibility of metals also affords a good means of
practical classification. Having reference to this difference, five
well-marked subdivisions admit of being established.
1. Fusible, and remaining liquid at the lowest heat of temperate
climes. There is only one metal which answers to these con-
ditions : it is mercury.
2. Fusible between 392° and 788° F., and passing off into vapor
when the heat is still further raised. The metals represented by
this subdivision are zinc, cadmium, lead, bismuth, antimony, and
arsenic or arsenicum.
3. Fusible at temperatures above 1830° F. : copper, silver, gold.
4. Not completely fusible by the strongest furnace-heat : man-
ganese, iron, nickel, cobalt, platinum.
5. Fusible in the hydro-oxygen jet : chromium.
ALLOYS. — Having taken a cursory survey of the classes and
subdivisions of which metals, practically considered, are suscep-
tible, we shall now proceed to describe the principal compound
forms of which metals are susceptible. The first of these which
presents itself is the class of alloys.
The term alloy in its most general acceptation means the mutual
combination of two or more metals. When one of the metals,
however, entering into combination is mercury, the result is not
OX METALLUBGIC CHEMI3TKY. 29
usually termed an alloy, but an amalgam. Alloys are practically
interesting to the metallurgist in two ways ; either the metals to
which a metallurgic process of extraction is applied are found in
the condition of native alloy — i. e. one naturally existing — or an
alloy results as the consequence of an intermediate metallurgic
process. The native state of gold with silver, and of platinum with
rhodium, indium, palladium, and its other associated metals, pre-
sent familiar instances of native alloys. The intermediate com-
bination of lead and silver resulting from the metallurgic process
of reducing galena, furnishes a good instance of the second. At
the present time the belief prevails — we may even say it is uni-
versal— that alloys are not always mere mechanical mixtures of
different metals, but are constituted in accordance with the laws
of definite chemical combination ; being no less atomic (to adopt
the language of the atomic theory) than oxides and salts are
atomic. It would lead us too far from the subject of metallurgy
to adduce the various arguments which exist in favor of the belief;
and indeed a superficial glance at the bearing of the hypothesis
would perhaps induce the practical metallurgist to pass it by as
devoid of utilitarian interest. Few subjects, however, are more
intimately related to the utilization of metals than those involved
in the seemingly abstract question of chemical composition, or of
mere admixture, in relation to alloys. An illustration very much
to the point is afforded by the manufacture of the alloy called
" silver-steel."
In the course of some experiments performed by Professor
Faraday and Mr. Stoclart, they discovered that silver when fused
with steel .in certain given proportions, entered into mutual com-
bination, and formed a valuable alloy. If, however, the quantity
of silver was increased above a certain proportion not yet quite
ascertained, the excess of silver was extruded from the metallic
mass during the process of cooling. This result at once affords
testimony as to the chemical constitution of the alloy, and points
to the practical advantages likely to be derived from a solution of
the question, "What are the exact or atomic proportions in which
steel and silver can combine ?" Granting, for the sake of argu-
ment, that the silver-steel be so far superior to ordinary steel as to
warrant its manufacture, the conclusion follows that it is a point
of the utmost importance to determine the exact maximum amount
of silver which steel can take up. Not merely would the addition
of every grain of silver beyond the indicated proportion be an
unnecessary expense, but such of the uncombined silver as might
be locked up mechanically in the alloy during the cooling process
would lessen its strength, and, indeed, impart a general deteriora-
tion of quality.
As a general rule, it may be stated that all metals which form
alkalies have a particular tendency to unite with those which form
acids. When two metals are alike in their affinities for oxygen,
they do not readily combine, and may often be separated by crys-
30 THE PRACTICAL METAL-WORKERS ASSISTANT.
tallization only, when both metals absorb nearly the same quan
tity of oxygen in forming their oxydes. Nearly all chemical
combinations liberate heat. Zinc and copper, when melted to-
gether, produce a high temperature. Where a mere mechanical
mixture of metals occurs in an alloy, it is characterized by dis-
tinct crystals being formed with one metal, between which the
other is visible. When an alloy is formed with proper equiva-
lents, no such disconnected crystals are observed. In cooling a
melted alloy, that composition which is most refractory crystal-
lizes first, and that which is most easily reduced to fluidity is com-
pelled to occupy the spaces between the crystals. Thus copper
and tin are fusible ; but in cooling, copper-tin crystallizes first, and
tin-copper last. Iron and arsenic are very fusible ; but in cooling,
iron-arsenic crystallizes first ; in consequence, the surface, when
cool, exhibits a perfect net- work of bright lines in regular forms.
In all of these compounds, however, portions of each alloy are
contained. When a bar of cold lead is dipped in mercury, the
pores of the lead become filled with mercury, but the mercury
also absorbs lead. When iron is strongly heated while imbedded
in carbon, as is the case when blistered steel is produced, the car-
bon penetrates to the very centre of the iron rods ; but no iron is
imparted to the carbon, because its atoms are not movable.
Alloys are more fusible than the individual metals, and will melt
at a lower temperature than the mean would indicate. Though
tin melts at 500°, and pure copper at 2,500°, equal parts of copper
arid tin do not melt at the mean 1,500°, but at a lower heat. Pure
iron is extremely refractory ; but when combined with arsenic and
phosphorus, it may be melted in a cast-iron pot without adhering
to it. Again, a composition of three metals is still more fusible
than their various degrees of melting would indicate ; and if their
component parts are according to the laws of chemical affinity, the
melting point is lower still. Need we repeat, after this, how im-
portant is the study of forming alloys in the smelting-furnaces ?
It is the degree of fusibility of the slags and metals, which deter-
mines the cost of the process.
Iron is rendered fusible by the presence of carbon ; but when
that substance is removed it becomes refractory, and can hardly be
melted. Tin is refined by oxidizing or evaporating sulphur,
arsenic, and other matters ; a process which renders tin less fusible
and more tenacious. Zinc melted in an iron pot, and exposed to
the air, exhibits dross on the surface ; its fluidity is diminished,
but its malleability is increased. A layer of carbon, or common
salt above ashes, prevents these phenomena.
Alloys are generally harder than might be expected from their
constituents; although there are exceptions to the rule. Silver
and arsenic render iron hard, although both metals are soft in
themselves ; copper and tin, both soft metals, become hard when
melted together in certain proportions; and zinc and copper makes
OX METALLUEGIC CHEMISTRY. 31
brass soft. Antimony causes all metals to become hard, but very
brittle. Iron mixed with a little antimony \vill cut glass.
The ductility of alloys is sometimes greater than might be ex-
pected ; in others, it is more brittle than the original metals. Al-
loys of zinc and lead, are very tenacious ; lead and antimony, very
brittle. Any alloy which is slowly heated and gradually cooled — •
annealed, that is — is softer than when the compound is suddenly
chilled ; hence the hardness of chill-cast iron.
The above-mentioned examples are types of many others, de-
monstrating that though metallic alloys occupy a less prominent
position than metallic oxides, sulphurets, chlorides, etc., neverthe-
less the conditions which regulate their existence must not be
neglected by the metallurgist.
The separation of the constituents of metallic alloys is accom-
plished by several methods. Of these the one most obviously
suggested by theory consists in a gradual application of heat up
to the point of melting the more fusible metal, and leaving the
other unfused. In this way lead is separated from an alloy of that
metal with copper. Scarcely less obviously suggested by theory
is the application of heat to effect the volatilization of one of the
metals entering into an alloy. In this way is mercury separated
in practice from alloys (amalgams) of mercury with gold, and mer-
cury with silver. In this way also is silver obtained from argen-
tiferous zinc.
The metallic constituents of some alloys admit of separation by
subjecting them to fusion and gradual cooling. During the cool-
ing process the metals of an alloy will in some cases separate in
layers according to their specific gravity. In other cases the sepa-
ration ensues from one of the constituents shooting into crystals
and becoming solid, thus furnishing a means of its removal. The
celebrated process of effecting the separation of silver from le ad,
known as Pattinson's crystallization process, is of this kind ; but
the most extraordinary circumstance in relation to it is, that the
lead or the metal of lesser fusibility is that which first crystallizes
out. The rationale of this curious phenomenon has never been
explained. Occasionally separation of two or more metals consti-
tuting an alloy is effected by means of acid- solution. The process
of quartation by which silver is dissolved out from an alloy of
that metal and gold, will serve as a familiar illustration.
METALLIC OXIDES. — We have already said that these are the
most numerous and the most important of metallic ores. -The
smelting of them depends on an application of the best prac-
tical means of removing oxygen. The relations of metals to
oxygen, and the relative facility wherewith they evolve oxygen
wholly or partially, have all been accurately determined by the
chemist. On the large scale, the exact agents employed in the
laboratory for effecting deoxidation cannot always be applied ;
nevertheless, chemical principles have to be followed as closelv as
circumstances will permit : therefore it will now be proper to ex-
32 THE PRACTICAL METAL- WORKER'S ASSISTANT.
plain the relations of different metals to oxygen in respect of the
comparative difficulty of removing that element from them.
The reduction of metallic oxides may be effected by the dry and
the moist processes. It is the former, however, which immediately
concerns the metallurgist, and to which we purpose to direct the
attention of the reader. The noble metals gold, silver, and plati-
num are characterized, as is well known, by the difficulty where-
with their respective combination with oxygen admits of being
effected. Conversely, the respective oxides of these metals are
characterized by facility of decomposition. The application of
heat alone, without the contact of any extraneous body, suffices to
liberate oxygen from the oxide of the noble metals, and of course
to evolve the metal.
All other metallic oxides require the agency of a second body
to effect their reduction, mere application of heat being insufficient;
and a consideration of the deoxidizing materials at the disposal
of the metallurgist, and employed by him, opens a field of great
utility and interest. The deoxidizing agent of greatest importance
to the metallurgist is coal in its several varieties, and the deriva-
tive materials yielded by its combustion. When coal is burned
in a furnace, the first product of combustion may be considered to
be carbonic acid gas ; but inasmuch as the latter is readily decom-
posed by permeating ignited pieces of solid carbon (coke), losing
a portion of its oxygen, and becoming carbonic acid gas, — we may
say that the products of the combustion of coal are firstly carbonic
acid; secondly, carbonic oxide and carbonic acid; and lastly, car-
bonic oxide alone. The latter in combination with heat is a most
powerful deoxidizing agent. Were it not for the production in
furnaces of carbonic oxide gas — were it necessary that the solid
carbon of the coke should be alone the deoxidizing body, then it
follows that every particle of the ore to be reduced must be
brought into intimate contact with the reducing body ; a process
involving more care and trouble than are compatible with large
metallurgic operations. The reducing agent being a gas, there is
no longer a necessity for that intimate mixture of fuel and ore
which would otherwise be necessary. Provided that the gaseous
results of combustion are placed under circumstances of readily
permeating the ore, the necessities of practice are amply subserved .
In many cases of reduction of the oxides of lead, silver, tin, and
copper, the fuel is actually contained in a furnace by itself, the ore
to be reduced being in another. There is great difference as to
the amount of heat at which the reduction of different metallic
oxides can be effected. The oxides of lead, bismuth, antimony,
nickel, cobalt, copper, and iron, require a strong red heat; whilst
the oxides of manganese, chromium, tin and zinc, do not lose their
oxygen until heated to whiteness.
Combinations of the metallic ores with oxygen take place in
certain definite proportions, and, so far as relates to most metals,
in definite quantities. There are three oxides of iron which in-
ON METALLUEGIC CHEMISTRY, 33
torest us here, namely — the protoxide of iron, which is a strong
base ; the magnetic oxide, a feeble base ; and the peroxide, which
is more of an acid than a base. Peroxide and protoxide of iron,
both infusible by themselves, form a fusible slag. Arsenic forms,
in all states of oxidation, an acid which nev£r melts with any other
acid, or with highly oxidized metals ; it being a requisite condition
of fusibility, that one of the constituents in which the other is
merely suspended must be fusible. This chemical relation admits
of a wide range, nor is the same substance in all its relations of
the same character.
The oxides of iron are always basic as to silic acid, but they are
acid in relation to oxide of lead. The study of the metallurgist
must be directed to these chemical relations, as well as to the de-
gree of fusibility of the compounds and the relation they bear to
the metal to be produced under their influence.
As a rule, it may be stated that the compounds of single equiva-
lents of metal and oxygen constitute a base of alkali, and that the
addition of more oxygen destroys that property. Thus the pro-
toxide of manganese is a strong base, and precipitates the protox-
ide of iron from a slag; but the peroxide of manganese is driven
out by the protoxide of iron. When carbon is present, one atom
of oxygen is absorbed by it from the peroxide of manganese, and
the iron is again driven from its union. This affinity of oxygen
for rnetal is most difficult to be overcome at a state of oxidation
half-way between the extremes. Protoxide of tin is easily con-
verted into metal, so is peroxide ; but the sesquioxide, interme-
diate between the two, presents much greater difficulties. Prac-
tically it is usual to smelt with the highest oxides, and convert
the ores into that state, in order, not only to remove the oxygen
from the metal, but also k) produce so high a heat as to fuse the
metal at the precise moment when the oxygen is removed.
Hydrogen and carburetted hydrogen gases must not be omitted
in our enumeration of the deoxidizing agents employed by the
metallurgist. The latter agent, carburetted hydrogen, is evolved
during the combustion of coal ; the former, when employed, as it
is, though sparingly, as a metallurgic agent, is developed by trans-
mitting aqueous vapor over red-hot coke. When this gas is pro-
duced by dissolving iron or zinc in a diluted acid, it is always
moist, and invaluable for the performance of any delicate experi-
ment; for the reduction of metallic oxides it should be dry, and
free from any foreign substance. Carburetted hydrogen or coal-
gas is used to reduce oxides under a low heat, the carbon which is
precipitated in the formation of the metal being removed by smelt-
ing. Hydrogen or carburetted hydrogen is applied in the assay-
ing process, by leading it into a glass tube which contains the ore
specimen in a proper form already heated. A gentle current of
gas is passed over the ore until no more is burned by it, which is
manifested by the escape of the gas in a pure form.
Xext to metallic oxides, metallic sulphides are of tre deepest
o
34 THE PRACTICAL METAL-WORKER's ASSISTANT.
importance to the metallurgist. Their reduction generally involves
the operation of roasting, a process to be treated of hereafter.
SULPHIDES. — All metals combine more or less with sulphur, and
form sulphides when sulphur is brought into contact with the
metal, in the absence of oxygen or chlorine. When oxides are
treated with sulphur in sufficient quantities to absorb all the
oxygen in forming sulphuric acid, the sulphur remaining com-
bines with the metal. When sulphates are treated in the presence
of carbon or hydrogen, the oxygen of the sulphuric acid is ab-
stracted, and sulphides remain. The chemical relation of sulphur
to metal is similar to that of oxygen — that is, the number and
equivalents of the sulphides correspond with the number and
equivalents of the oxides of the respective metals — causing them
to be more fluid and brittle when cold, and impairing their duc-
tility when hot Large quantities of sulphur cause a low degree
of fusibility* which is shown in the sulphurets of antimony, lead,
copper, and iron, the fusibility in each decreasing more rapidly
than the evaporation of sulphur. Iron pyrites melts at a low red
heat; but when reduced to half its original quantity, by evaporat-
ing the sulphur, it requires a strong white heat to melt the sul-
phides. The presence of free oxygen is required for the removal
of sulphur; nor can it be removed entirely when carbon, hydrogen,
or any other reducing agent is present, an oxidizing influence and
thorough exposure of the metal to oxygen being necessary.
Nevertheless, the partial decomposition which certain metallic
sulphides undergo, when heated without the access of atmospheric
air, is to the metallurgist a consideration of importance. Galena
treated in this way suffers partial decomposition ; so, in like man-
ner, does the monosulphuret, or monosulphide of copper, — a suf-
ficient amount of sulphur being evolved from it to yield disulphide
of copper as the permanent fixed result. The higher sulphur
combinations of iron, or chemically speaking, the sulphur salts of
that metal, generated by the combination of two sulphurets or sul-
phides, also give a portion of their sulphur when exposed to high
heat in close vessels. Monosulphide of iron, however, does not
yield up any of its oxygen by the mere process of heating in close
vessels. The sulphide of zinc (zinc blende) is unchanged by the
highest temperature ; so, in like manner, is the sulphide of silver.
The sulphides of gold and of platinum are decomposed when
heated into sulphur and their respective metals. The sulphide of
mercury can be distilled without change. Sulphide of antimony
melts at a high red heat, afterwards distils over unchanged. The
mono and the ter-sulphide of arsenic (orpiment and realgar) both
fuse, and distil without undergoing any decomposition.
By far the more important and usual method, however, of effect-
ing the reduction of metallic sulphides, consists in exposing them
to the combined agency of heat and atmospheric air — constituting,
in point of fact, the operation of roasting. Usually, the change
which ensues during the operation of roasting,, is the conversion
ON METALLUBGIC CHEMISTRY. 35
of sulphur of the sulphide into sulphurous acid gas, which escapes:
ths original sulphide, either losing a part of its sulphur, and being
thus reduced to the lower stage of sulphurization, or else, losing
the whole of its sulphur, oxygen is absorbed in place of the latter.
Occasionally the sulphurous acid first generated absorbs the neces-
sary amount of oxygen, to change it into sulphuric acid, which
combining with the metallic oxide simultaneously generated, gives
rise to the sulphate of an oxide. This latter is the case when
galena (sulphide of lead) is roasted, the final result of the opera-
tion being oxide of lead, and sulphate of oxide of lead. This
change is eminently favorable to subsequent metallurgic operations
of which galena is the subject. If the galena be argentiferous, the
following reactions ensue : The mixture of oxide of lead and sul-
phate of the same oxide being heated to whiteness in contact with
silver (of the argentiferous galena), oxidizes the silver by decom-
position of the sulphuric acid, of the sulphate and oxide of lead ;
hence there results a mixture of oxide of silver and of lead — a
mixture easily dealt with, and deoxidized by a subsequent opera-
tion. The sulphide and disulphide of copper are changed by
roasting, into dioxide of copper and sulphurous acid, and sulphate
of the oxide of copper, which latter, when, the temperature is
raised to the highest pitch, evolves the whole of its sulphuric acid
and oxygen ; leaving metallic copper. Monosulphide of iron by
roasting undergoes many progressive changes ; beginning with the
formation of protoxide of iron and sulphurous acid, and ending in
the development of sesquioxide of iron. Sulphide of zinc (zinc
blende) slowly changes under the influence of roasting, first into
oxide of zinc, and sulphate of the oxide ; then into subsulphate of
the oxide ; and, lastly, into oxide exclusively. Sublimate of bis-
muth changes, under the influence of roasting, into oxysulphuret :
sulphide of silver is decomposed, and yields metallic silver. Ter-
sulphide of antimony changes under roasting into antimonious and
antimonic acid. The sulphide and the sesquisulphide of arsenic
are changed into arsenious and arsenic acids.
By a modification of the same process, sulphide of nickel ad-
mits of decomposition into a mixture of oxides and sesquioxides
of that metal. Sulphide of cobalt is also decomposed into a mix-
ture of oxide of that metal and sulphate of the oxide. Finally,
the sulphides of gold, platinum, and mercury are also reduced to
the metallic state, sulphurous acid gas being evolved.
Another element equal in importance to oxygen, requires the
attention of the metallurgist. Chlorine has a tendency to induce
metals to crystallize, and causes consequently fluidity and brittle
ness. Chlorine removes all other matter from metals when the.
latter are in a state of fusion. Carbon, sulphur, and phosphorus
are drawn off by it, and, if the heat is continued, the chlorine it-
self escapes with a portion of the metals, but only when a minute
proportion is present; it is thus a powerful element in the purifi-
cation of metals. Lead smelted from chlorides is purer than from
36 THE PRACTICAL METAL-WORKER'S ASSISTANT.
oxides and sulphurets, and its proper application to smelting and
refining purposes has a most beneficial influence. Zinc does not
readily combine with iron unless chlorine be present ; it removes
oxygen from the protoxides, thus purifying the surface and pre-
paring it for closer union with an alloy. All metals smelted under
the influence of chlorine, are inclined to oxidize, unless it is re-
moved entirely. It is harmless to the metals, powerful as a means
of fluxing slags and ores, and producing fluidity ; its use, therefore,
ought to be much more extended than it has been.
CALCINATION, AND ROASTING. — These processes are more fre-
quently made use of than any other operation had recourse* to by
the practical metallurgist for effecting the elimination of sulphur
and other volatile substances from the ores which are sulphides or
sulphurets. No agency is so commonly employed as this, although
the mention of a few others should not be omitted. Amongst these
may be enumerated the combined application of heat and aqueous
vapor ; of heat, and the decomposing agent of a metallic oxide ;
finally, of heat, and the decomposing agency of alkalies, alkaline
earth, and their combinations. As a general rule, however, we
may regard all other metallurgic processes having reference to the
decomposition of sulphurets, rather as preliminary assay operations
than the final processes capable of adoption by the manufacturer.
The process of calcination is generally adopted to remove vola-
tile substances. Iron and zinc ores are heated to expel water from
them, and iron, lead and zinc, are calcined to expel carbonic acid.
Water will escape by the application of a gentle heat ; but if much
clay be present with the ore, it adheres tenaciously to the mineral.
Calcination is most conveniently performed in a crucible, because
no stirring of the mass is required. The heat of an air furnace is
generally sufficient for the performance of this operation.
The operation of roasting is performed by various processes, de-
pending on the nature of the ore, the quantity of the fuel, and the
object in view. Boasting in heaps in the open air is the method
most generally adopted with iron ore, pyrites, and ores which can
bear a strong fire. The operation consists in spreading over a
plane surface of ground billets of wood, or lumps of mineral coal,
from six to eight inches thick, the interstices between the coarse
fuel being filled up with chips of wood, charcoal, coke, or coal.
Over the fuel thus prepared, according to the kind of ore, is spread
a layer of from twelve to twenty-four inches in thickness. Coarse
ore, which will bear a great heat, may be piled pretty high ; but
fine crushed ore from the stamps, and ores which smelt easily —
such as sulphurets or arseniurets — should not have too much coal
in a body, nor the ore piled over high.
Alternate beds of fuel and ore are thus formed, and roasting
heaps accumulated, which are in many cases extremely large, re-
taining the fire for a long time.
Boasting means heating a substance to such a point that the
mineral does not melt, but at which the volatile substances are ex-
ON : METALLURGIC CHEMISTRY. 37
pelled, and as much oxygen combined with the ore as it can absorb.
In some cases, chlorine, carbonic acid, or steam, is required along
with the air. In other instances, the object is to oxidize the ore
to a higher degree, to drive off volatile matter, or to reduce the
ore to metal, and evaporate it, as in the case of arsenic, zinc, and
antimony.
The tendency of carbon to unite with metals is slight and cir-
cumscribed. Only two metals, considered in a metallurgic sense,
are amenable to this kind of combination, — copper and iron.
Nevertheless, they are the most important of all metals ; and with-
out the carburets of iron (cast-iron and steel), the most useful pur-
poses to which iron is now applied could never have been sub-
served. The union of carbon with copper is only productive of
inconvenience, and the care of the metallurgist is devoted to effect
the removal of the former ; but in the case of iron, though on one
hand the removal of carbon is a metallurgic process highly de-
sirable in order that soft wrought-iron may result, nevertheless, on
the other hand, the problem of causing the union of soft iron with
carbon is one of importance equally great ; for on its successful
issue depends the conversion of iron into steel.
As regards the theory of the metallurgic processes had recourse
to for effecting the removal of carbon, they are such as naturally
suggest themselves from a chemical consideration of the properties
of that non-metallic element. Carbon is the most ordinary ma-
terial of combustion known to man, — it is the very type of com-
bustible bodies. To deprive a carburet of its carbon, therefore,
nothing seems more natural than to burn it away. This is indeed
the process usually followed. It lies at the basis of iron-refining
and puddling ; still more obvious is the application of the combus-
tive energy in the new operation of Mr. Bessemer. Combustion,
nevertheless, is not the only agency taken advantage of for effect-
ing the removal of carbon from iron. A very elegant process for
converting steel or cast-iron into soft or decarbonized iron, consists
in exposing an article fabricated of either of these materials to
heat in contact with iron oxide. The chemical agencies thus in-
volved are sufficiently obvious. The oxygen by its affinity for
carbon at an elevated temperature unites with it, forms carbonic
acid, and is evolved, leaving the iron, to the extent of the removal
of carbon thus effected, pure. The process in question unfortu-
nately has but an application restricted to a limited number of
articles of inconsiderable dimensions.
The union of soft iron with carbon, or, in other words, the
formation of steel, is usually effected by the process known as
cementation. It consists in stratifying bars of iron with charcoal
in an iron case, and subjecting the whole to furnace heat until the
desired union of the carbon with the iron has been effected. The
chemistry of this union is very peculiar : furnishing an almost
unique example of combination ensuing between- bodies neither
fluid nor gaseous, and contravening the long- accepted chemical
THE PRACTICAL METAL-WORKER7* ASSISTANT.
axiom, Corpora non agunt nisi flnida. Perhaps however, after all,
the exception is more apparent than real. Laurent was of opinion
that the carbon thus entering into combination with iron, and
forming steel, became actually vaporized by the heat employed.
Stammer advances another hypothesis. He believes that the play
of affinities resulting in the union of carbon with iron, is more
complex than had up to his experiments been imagined. He in-
fers that a mixture of iron and oxide of that metal, when brought
to an elevated temperature, as in the process of cementation, in
contact with carbonic acid gas, robs the latter of its oxygen, thus
liberating carbon ; which, whilst still in this condition, unites with
the metal to form a carburet.
Though the great magazine of phosphorus in creation is the
bones, and some of the fluids of animals, nevertheless, phosphoric
acid, combined with oxides of metals and constituting phosphates
of these oxides, give rise to a small though important group.
Perhaps no element wherewith metals are naturally found in com-
bination is more difficult to separate effectually, or exerts a more
deteriorative influence when present, even in minute quantities,
than phosphorus. The processes usually had recourse to by the
metallurgist for effecting the separation of phosphorus, are based
upon the employment of some body which manifests a strong
affinity for phosphorus at elevated temperatures. Of this kind is
chalk, which is sometimes employed for the purpose of separating
phosphorus from iron.
Occasionally, though not very often, the metallurgist has to deal
with the extraction of metals from theiy salts, both oxygenous and
haloid. This kind of extraction, too, involves not merely the dry
process, but also the use of chlorine and of acids. Platinum is a
metal which has to be dealt with exclusively by the process of
moist solution. Limiting our observations for the present to the
case of dry operations, we find that certain metallic salts are de
composable by heat alone, whilst others require the agency of
some collateral reducing body. Most of the salts of the metals,
gold, platinum, and silver, are characterized by their facility of
complete decomposition by the mere application of heat. Of this
change, the chlorides of gold, of platinum, and the sulphate of the
oxide of silver, present familiar examples. Many other metallic
salts when subjected to the agency of heat, instead of being re-
duced to the metallic form, yield their several oxides. The sul-
phate of iron and the sulphate of copper are of this class, — yield-
ing, when sufficiently heated, oxides of the respective metals.
To the practical metallurgist, the most interesting series of saline
decomposition by fire, and deoxidizing materials, are those in
which the sulphates of different metals are concerned. Sulphates
differ merely from sulphides (viewed as to their composition) in
the mere circumstance that the former contain oxygen, whilst the
latter do not. Hence, when sulphates are heated in contact with
coal, coke, or other deoxidizing matter, oxygen is frequently re-
SPECIAL METALLURGIC OPERATIONS. 39
moved and a sulphide remains. The relative facility of this kind
of decomposition varies for different sulphates, but it furnishes a
type of most of the decompositions which ensue when sulphates
are exposed to the combined agency of deoxidizing materials and
heat. Of all the salts which come under metallurgic cognizance,
the chlorides next to the sulphates are most important. The re-
duction of the chloride of silver forms the basis of the mode of
silver extraction followed in America, Hungary, and various parts
of Europe, — the reducing agent being iron. Various other methods
of reducing chlorides to the metallic state are followed in the pro-
cesses of metallic assaying ; and, although not much involved in
the practise of metallurgy on the large scale, are still of great im-
portance to the metallurgist. The reduction of chloride of silver
by heating with alkalies ; of the chlorides of certain metals by
the contact of another metal; and of the chlorides of gold and
platinum by sulphurous, oxalic, ars.enious, and formic acids, sul-
phate of iron, and a few other reagents, — are familiar examples.
CHAPTER II.
SPECIAL METALLUBGIC OPERATIONS.
now come to the principles on which metallurgic processes
are based, and the practical application of these principles. Me-
chanical and chemical sciences are here involved, — the former to
effect a due comminution of the extracted ore from foreign impu-
rities; the latter to complete this separation and evolve the metal
in a condition as near that of absolute purity as may be possible
or desirable. The mechanical part of metallurgy can only be dis-
cussed advantageously hereafter ; in this introduction, therefore,
we shall limit ourselves to an exposition of the chemical princi-
ples of metallurgic operations.
Between abstract chemistry, if the term "he allowable, and tech
nical chemistry, there seems a wide difference at a first glance
The only real distinction between them, however, will be found to
be one of degree. The principles are the same, and both are
amenable to the same laws : the laboratory chemist, however, hav-
ing more agents at his command — being little amenable to consid-
erations of profit — more readily carries these indications out to
their several finalities.
The chemical part of metallurgy has for its object the separation
of various substances, and the isolation of a few, by the operation
of chemical affinities ; being amenable thus to ordinary rules of
chemical guidance, the first of which is based upon the law that
chemical action takes place (with few exceptions, and those doubt-
40
THE PRACTICAL METAL-WORKERS ASSISTANT.
ful) between portions of matter the cohesion of which is slight.
Keversing the proposition, we may also say that chemical decom-
position is effected by loosening the state of cohesive affinity.
Of the three forms in which matter is found, namely, the solid,
the fluid, and the gaseous state, respectively, it is evident that the
two former are most under the control of cohesion; — gases, indeed,
are often said to be absolutely devoid of cohesion as between their
particles ; a proposition which, though chemically unsound, may
be considered to 'be practically correct.
The metallurgist, then, in effecting his numerous decompositions,
proceeds to diminish the cohesive force by which the particles of
his material are held together. He begins by mechanical pro-
cesses— by hammering, grinding, stamping, etc. When these can
go no further, he has recourse to chemical means. The problem
now is to liquefy, or to gasify — usually the former, though many
important mineralogical operations involve the production of ga.s,
or at least of vapor ; for gases and vapors may be generally re-
garded as identical. Supposing liquefaction to be the object in
view, the metallurgist has the choice, theoretically, of dissolving
his substance in chemical menstrua or of fusing it by heat. The
former alternative is superior in the correctness of its results, and
for that reason is usually adopted by the laboratory chemist ; but
it is so expensive, and slow, and inapplicable where large masses
are concerned, that it is never adopted by the metallurgist, other-
wise than by necessity. With the exception of platinum and its
associates, all worked exclusively by the process of solution in
chemical menstrua — by the moist process, in point of fact — gold
occasionally, and a few of the common metals under certain pecu-
liar conditions, the moist process of effecting solution of cohesive-
ness may be regarded as beyond the pale of applied metallurgy.
We have thus limited the metallurgist to the agency of fire ;
and we have assumed, as is most usual, that the object of furnace-
heat shall be to reduce the material to the condition of fluidity.
We might, therefore, at once, pursuing the thread of demonstra-
tion, enter upon the theory and opera-
tion of fluxes, were it not that a case
of effecting chemical decomposition
by the formation of gas or vapor some-
times precedes and therefore claims
precedence in our remarks. Many ores
either contain substances naturally
volatile or which generate, under the
combined influence of heat and air,
volatile combinations. Sulphur and ar-
senic are prominent examples of this
kind, and serve well to illustrate that
application of a chemical law which
is involved in the metallurgic pro-
ress of roasting or calcination; respecting which sufficient par-
SPECIAL METALLURGIC OPERATIONS.
41
ticulars in an earlier part of this introduction have been already
given.
The process of roasting is variously modified to accord with the
peculiarities of certain metals, or to gain the precise end desired.
In some cases it is no more than the process known to chemists as
dry distillation ; in other cases, its success depends on the com-
bined agency of an atmospheric current as applied, for instance,
to the evolution of antimony.
Though the metallurgic operation of roasting involves a well-
marked case of gasefaction applied to a definite end, yet similar
results are obtained under different forms of apparatus. The oper-
ations involved in the production of mercury and zinc are famil-
iar examples. Both these metals
are remarkable for their extreme
volatility, the first especially so :
hence the process of metallurgy
adopted in their production is not
one of smelting, properly so called,
or of roasting as popularly under-
stood, but as one of veritable dis-
tillation. Mercury is frequently
produced by simple sublimation,
without the addition of flux or
coal, so also is arsenic; but in
most instances carbon, and such
substances as decompose the ore,
are added. In the mercury dis-
tillation-furnace here annexed
(Fig. 1) the similarity to ordinary
distillation vessels and receivers
is sufficiently obvious; not very
remote, either, is the similarity to
the ordinary distillation apparatus
shown by the Belgian furnace for
zinc extraction (Fig. 2). There is
no difficulty in smelting zinc un-
der cover of carbonate of soda
and potash with carbon, but this
is an expensive flux, and, when
not closely watched when fluid,
the loss may exceed the value of
the metal obtained. It is for these
reasons found good economy to
mix the zinc blende with iron;
although the heat required by this
process is much greater than for
smelting, it is asserted that distil-
Fig. 2.
lation is the cheaper process. The apparatus here figured is a ver-
tical section of a furnace with its retorts, of which there ai'e as
42
THE PRACTICAL METAL-WORKERS ASSISTANT.
many as twenty-two. They are placed about two inches apart
from .each other to admit the passage of hot -gases from the fur-
nace. The metal which condenses in these gently-sloping pipes,
requires to be raked out every two hours to prevent them from
being choked up, and twelve hours are required to work off a
charge. Perhaps the various parts of an English zinc oven may
not be quite so suggestive of a distillatory process ; nevertheless
they are representatives of a form of distillatory apparatus per-
haps more ancient than any — a form known to the alchemists, and
described by them under the name of destillatio per dcscensum, (Fig.
8). A vertical section is given of this apparatus. They are some-
times round, sometimes square, having six or eight crucibles in-
serted in one furnace, an iron
pipe inserted into the bottom
of the crucible conducting the
metal into a reservoir, which
is filled with water.
The theory of this process
is very simple : the oxide of
zinc mixed with carbon is re-
duced to metal on being ig-
nited; and the metal, being
volatile, passes in the form of
vapor to the receiver, where it
is condensed in the form of a
crude impure metal, which re-
quires a further process of re-
fining before it is fit for commercial purposes.
FLUXES. — Assuming the process of roasting to liave been neces-
sary and to have been applied, and that a metallic substance still
remains to be extracted from the non- volatile residue, a process of
fusion must be had recourse to ; it is called smelting. A slight
chemical consideration of the materials wherewith metals are or-
dinarily combined, will bring to mind the fact that some are really
or practically infusible. But fusion the metallurgist must have :
the theoretical choice was before him of choosing between the
moist or solvative, and the dry or igneous process of effecting
liquidity. He was driven by practical considerations to accept the
latter ; therefore fusibility is a condition so indispensable to success
in his future operations that he must have it. How, then, Was ho
to solve the problem of effecting the fusibility of things which
are by their nature infusible ? Chemistry renders the solution of
this problem easy : there are many substances which, though in-
fusible when heated by themselves, fuse readily enough when
heated in combination; hence arises the theory of fluxes and flux-
ing, these terms being respectively applied to substances which'
impart igneous fluidity, when heated with other substances, and to
the manner of using them. Silica, or silicic acid, is an infusible
body when heated alone; nevertheless it fuses when sufficiently
Fig. 3.
SPECIAL METALLURGIC OPERATIONS. 43
heated in contact with potash, soda, or their respective carbonates ;
and less readily when heated in contact with alkaline earths.
Hence if the metallurgic problem were to present itself, of ex-
tracting a metal by fire from a mixture of the same with silica
(chemically silicic acid), potash, or soda, or their respective car-
bonates, would be had recourse to in preference to all others, if
considerations of profit and loss did not intervene. The price of
the alkalies and carbonates of alkalies does not admit of their
common application to the purposes of a flux on the large metal-
lurgic scale ; wherefore the smelter, not being able to use the flux
which chemistry proclaims to be the best, contents himself with a
substitute as near to the theoretic quality as may be practicable.
Thus where alkalies, or carbonates of alkalies, would have been
employed to facilitate igneous fusion in the laboratory, and on the
small scale — probably lime, or carbonate of lime, would be em-
ployed in the larger representation of the process as performed by
the metallurgist.
Not only do the alkalies and their carbonates perform the func-
tions of fluxes to silicic acid, but also to several metallic oxides ;
amongst which those of lead, copper, and iron, may be cited as
familiar examples. Every person knows that flint-glass, 'as it is
called, contains oxide of lead; that black bottle-glass contains ox-
ide of iron, — combinations which illustrate, perhaps, as well as
any we could adduce, the quality of the alkalies which imparts to
them the power of a flux. When it is considered that nearly all
the colors which can be imparted to glass, nay, which are imparted
to porcelain and enamel, are referable to combinations of metallic
oxides with silicic acid, a still further notion will be conveyed of
the extensive range of combination which may be produced by
silicic acid under the influence of igneous fusion. <-
Next, perhaps, to potash and soda, in respect to its large range
of agency as an igneous flux, comes borax. Seldom is it that the
assayer in his laboratory operations on mineral ores by fire dis-
penses both with alkalies and with borax ; but here in this case,
again, considerations of expense restrict the application of this
material to the laboratory, and the smelter is obliged to content
himself with fluxes much lower in the scale of chemical power and
efficiency. Perhaps, however, there may not be so many advan
tages lost from the non-employment of laboratory fluxes on the
large scale as is sometimes imagined. To adopt soda, or potash,'
or borax, though compatible with the economical ari^ingements of
the laboratory chemist, who will not hesitate to ruin a crucible at
each operation, might still accord very ill with the economy of
furnace-building. The alchemists tried to discover a fluid which
should have the property of dissolving all things wherewith it
might come into contact. They neglected to reflect that a neces-
sity would arise for a vessel to keep it in. It might be thus with
metallurgists on the large scale, if laboratory fluxes were cheap
enough, and plentiful enough, to be adopted on the large scale.
44 THE PBACTICAL METAL-WORKER'S ASSISTANT.
Though the number of fluxes which the metallurgist has at his
command for large operations of smelting be inconsiderable by
comparison with those employed in laboratory operations, never-
theless the process of assaying is one so important to the metal-
lurgist that every flux known to the chemist deserves his con-
sideration. Under the subject of assaying, therefore, to *be ad-
verted to hereafter, the chemical agents will be fully discussed:
The preliminary operation of dressing having been performed
on a mineral, also the further operation of roasting if necessary,
the final operation of smelting naturally follows. After the gen-
eral statement we have given of the nature and properties of fluxes,
it will be seen that the operation of extracting metal from a metal-
lic ore by smelting, consists in subjecting it to furnace-heat in ad-
mixture with some flux, — the object of the latter being twofold.
Primarily to liquefy and dissolve away refuse matters by themselves
infusible ; and, secondarily, in some cases to aid the decomposition,
by the result of which the metal is evolved from its combinations.
It remains now, for the completion of our sketch of the appliances
of metallurgy, that we indicate the peculiarities of the different
furnaces, and the appendages by means of which the operation of
smelting is effected.
FURNACES. — The various forms of furnaces admit of division
into two well-marked primary classes. One class in which the
material to be acted upon is brought in direct contact with fuel ;
the other class in which the acting fuel and the material acted upon
are separated from each other.
Either of these furnaces may be supplied with air from a blast
of some kind, or they may depend for their supply of air on the
draught of a chimney -shaft. Accordingly, in reference to these
peculiarities we establish a division of furnaces into blast-furnaces
and wind-furnaces. The first class of furnaces, or those in whicli
the material and the fuel are placed in contact, differ in form and
general intention, according to certain obvious peculiarities of con-
struction. Some merely consist of a flat expansion or hearth, upon
which the fuel may either smoulder and develop a long-continued
gentle heat, as in the ordinary lime-kiln ; in the kiln or hearth
upon which copper pyrites and copper matte are heated or roasted,
and in many similar forms of hearth-furnace employed by metal-
lurgists, chiefly to accomplish roasting operations ; or the fuel moy
be urged to almost the highest degree of heat of which a furnace
is capable, as -we see exemplified in the smith's forge. A modifica-
tion of this form of furnace is employed in Great Britain in the
smelting of considerable quantities of lead ore. If, however, it be
desired to raise the intensity of furnace-heat to the highest point,
the hearth-construction of furnace must give place to others on the
type of a cylindrical or conoidal vessel. Perhaps the highest
degree of furnace-heat known, is yielded by large iron blast-
furnaces.
Usually the aid of an artificial blast is only Bought for the first
SPECIAL METALLURGIC OPERATIONS. 45
division of furnaces, namely, those in which the fuel and the ma-
terial to be acted upon are employed together. This, however, is
by no means universal. To furnaces in which the substance acted
upon does not come into contact with the fuel used, the term re-
verberatory furnace is applied. Amongst other metallurgic ap-
plications of this third kind of furnace, those of iron puddling and
balling may be especially mentioned. •
Still more important than an acquaintance with the various
terms conventionally applied to furnaces, to the form of their con-
struction, or the objects they are intended to subserve, is a full
comprehension of the chemical principles upon which their effi-
ciency depends ; aud with that we have to deal here. A furnace
may be said to be a contrivance for giving the best practical effect
to the laws of combustion as directed to some practical end. It
will hence be proper that we take a casual glance at these laws, as
a branch of chemical physics applied to metallurgy. All ponder-
able bodies are conventionally divided into combustibles and sup-
porters of combustion ; thus, for example, coal is said to be com-
bustible, and air, or rather the oxygen contained in the air, is said
to be the supporter of combustion under the usual circumstances
involved in the ordinary combustion of coal. This division, though
usual, is purely conventional ; the function of combustion being, in
point of fact, a result of chemical action between two agents, and
appertaining to both ; whence, in strict language, coal or the
materials of coal and atmospheric oxygen gas are equally the sub-
jects of combustion, and therefore combustible. Nevertheless the
conventional distinction between combustibles and supporters of
combustion has attained a certain significance, rendering it con-
venient of application in a practical sense. If we mentally review
the substances of combustion they are such as most obviously
present themselves to common observation. Before the employ-
ment of hydrogenous gas for heating and illuminative purposes,
all popularly known combustibles presented the qualities of being
visible and tangible ; their combustive property was known long
before the theory of combustion had been suspected, and at periods
when the existence of gases was looked upon as matter to be
doubted or disbelieved ; no wonder, then, that the new power in-
volved in the combustive operation was so long unsuspected, and,
when discovered, allowed a subordinate place only. Though all
material bodies be impressed with the quality of ministering to
the combustive function, either in the sense of a combustible or a
supporter of combustion — nevertheless, the bodies which are of a
nature enabling man lo realiee them as combustibles are few.
Above all things it is necessary to the efficiency of a combustible,
practically considered, that the result of its combustion shall be
gaseous. When pure charcoal burns, no residue or ashes are left ;
the sole result of combustion is a gas, which, by reason of its
nature, passes away. Even when ordinary charcoal is used, the
ashes are but inconsiderable ; and if coke or coal be the fuel em-
46 THE PRACTICAL METAL-WORKERS ASSISTANT.
ployed, the amount of solid residue still bears but inconsiderable
proportion to the mass of fuel originally used. Guided by the
limiting consideration of gaseous products, it is easily seen that the
only class of bodies having any claim to be regarded as combus-
tible, in a practical sense, are two — the hydrogenous and the car-
bonaceous forms. All the naturally occurring fuels present us
with a mixture of these : coal in all its varieties, wood, and peat, so
obviously bearing out the proposition that no illustration is re-
quired. Reference to the chemical condition of carbon and of
hydrogen respectively when burned will bring to mind the fact,
that in proportion as hydrogen predominates, so will the combus-
tion be more flaming ; and conversely, in proportion as hydrogen
is absent, so will the resulting combustion be of the incandescent
or glowing kind, like that of ignited charcoal. Of late much
attention has been devoted to the problem of ascertaining the com
parative value of fuels ; but we may here remark that the deduc-
tions have not been attended with a corresponding amount of
practical success, chiefly because of their too literal and exclusive
application.
The real amount of heat capable of being developed by the given
weight of a combustible by refined chemical means, is so involved
with other conditions in practice as to be of itself little worth.
The mechanical aggregation of any particular combustible, is at
least an element of consideration of equal value to its real chemical
power of evolving heat. The truth of this proposition is amply
borne out by the familiar operations of coking and charcoal
making. "Weight for weight, coal has more combustible heat-gen-
erating matter, than coke and wood, or than the charcoal made
from wood. Nevertheless the mechanical or physical conditions
of coal and wood are such, that they are totally unadapted to many
of those heat-generating operations which coke and charcoal effi-
ciently subserve. The fixedness of carbon and the volatility of
hydrogen suggest the cases in which the superior absolute heat-
developing power of the former would be more than compensated
by the inferior localized heat-generating power of the latter. Ac-
cordingly, theory indicates, and practice confirms the indication,
that in all cases wherever it is desired to bring the fuel and the
material to be fused into actual contact, a non-hydrogenous fuel,
such as coke and charcoal, is to be sought. When, however, the
substance to be acted on is situated apart from the fuel, then the
latter may, though not necessarily so, be hydrogenous. Even the
carbonaceous fuels may be made to yield flame by particular treat-
ment. If atmospheric air be supplied to the extent of ministering
to the full wants of carbonaceous combustion, there is no flame,
because the carbon is immediately and entirely changed into car-
bonic acid ; if, however, the supply of air be more scanty, or if the
fuel be so arranged that the carbonic acid originally formed has to
permeate white-hot carbon, it is practically deoxidized, changed
into carbonic oxide, a combustible gas : hence, flame ensues. So
SPECIAL METALLUKGIC OPERATION'S^* 47
' / ,
important lid it seem to obtain a strongly -flaming -fuel i6//tj$e in
the rjeverberatory furnace operation of iron puddling, that noftt,
merely gas-yielding bodies, but gaseous mixtures have actually
been proposed, and to a limited extent carried into practice ; ntoiey
over, the unconsumed inflammable gases which escape from iron-,* |
blast smelting furnaces is sometimes collected, and applied as a
heating agent. Probably, however, the latter application is one in
a wrong direction. It may be, and probably is true, that if an
escape of combustible gas take place from one of these furnaces
sufficient to be of consequence as a heat-giving agency, this cir-
cumstance suggests an imperfection in the economy of the furnace.
Instead of endeavoring to collect the escaping gas to be used as
a combustible therefore, it might be preferable to take measures
for burning the gas while yet in the furnace, thus rendering the
heat developed by its combustion effective in the furnace operation.
Many iron-manufacturers who at one time used the inflamma-
ble gases of their furnaces as a heating agent, have since aban-
doned the practice ; and a sort of inferential testimony to the disad-
vantage of the process is afforded by the well-marked and ingenious
effects developed in the primary operation, if the collecting of the
gaseous results be made lower down in the body of the furnace than
a line coincident with the termination of the first third of the
vertical height of the furnace shaft. If the gases be withdrawn
higher up than this, they are mixed with so much combustible
material such as nitrogen and carbonic acid, that they are worthless
as heating agents; if they are withdrawn lower down, the smelt-
ing operation is prejudiced by the removal of carbonic oxide
• — an important agent in accomplishing the .reduction of iron
ore.
The subjoined table will show the composition of the gases thus
withdrawn from iron furnaces in three different works, i. e. Yeck-
erhagen, Clerval, and Barum :
(I.) 15£ ft. (II.) 18 ft.
Nitrogen .... 62-47 — 58-115 . . 64-28 — 63'20
Carbonic acid . . 3*44 — 13'76 . . 4'27 — 12-45
Carbonic oxide . . 3O08 — 22'65 . . 29-17 — 18-57
Carburetted hydrogen 2-24— O'OO . . 1'23— 1-27
Hydrogen . . . 1-77 — 1'77 . . 1-05 — 4-51
100-00 100-00 100-00 100-00
Regarding the composition of the gases from Veckerhagen and
the gases from Barum (I.) and those from Clerval and Barum (II.)
as almost mutually identical, a mean may be taken in hereafter
calculating their relative values. The following table represents
the mean composition b}r volume :
48 THE PRACTICAL METAL-WORKER'S ASSISTANT.
Veckerhagen and Clerval and
Barnm (1.) Barum (II.)
Mean. AleaA
Nitrogen 63-4= 60'7
Carbonic acid 3'9 13-1
Carbonic oxide . , . . . 29'6 2O6
Carburetted hydrogen ... 1/7 O6.
Hydrogen 1-4 5'0
100-00 100-00
A composition by volume which accords with the following com
position by weight:
A. B.
Nitrogen 63'4 597
Carbonic acid 5'9 19'4
Carbonic oxide 29'6 20*2
Carburetted hydrogen ... I'O 0*3
Hydrogen 01 (H
100-00 100-00
The former, however, are not the only gaseous constituents
which are evolved unconsumed from coal and coke-burning fur-
naces. Occasionally hydrogen and carburetted hydrogen are de-
veloped, as was found to be the case by Ebelmen in the gaseous
evolutions of furnaces at Vienne and Port L'Eveque.
While on the subject of the utilization of combustible gases
which escape from iron-furnaces, it may be well to indicate that the
idea first originated in 1812, at which date Abberlet obtained a
patent for the application of gases thus developed to metallurgical
purposes. In 1830 an attempt was made at Holsbriicke, near Frei-
berg, to employ the flame of coal-gas as the source of heat for
cupellation. In neither case, however, was the proposition carried
out to complete success, or, indeed, fully inaugurated. The merit
of accomplishing the latter is due to Faber clu Faur, who, about
the year 1838, tested the value of the suggestion on the furnaces
of some iron- works at Wiirtemberg.
However doubtful the advantages may be of collecting gaseous
matters from iron furnaces and utilizing them as fuel, the prospec-
tive advantages of employing combustive gases in this way have
seemed considerable enough to warrant the invention of several
contrivances with this end specially in view. In France, and more
especially in Silesia, combustible materials are gasefied with spec-
ial reference to employment of the resulting gas in furnace opera-
tions. We have already adverted to the disadvantages which
the iron-master encounters from the necessity he is under of
smelting with a fuel holding injurious quantities of sulphur, phos-
phorus, and some other impurities. Reflection on these conditions
SPECIAL METALLURGIC OPERATIONS.
will indicate the advantages which should theoretically accrue from
the substitution of gaseous combustibles devoid of such matters.
Practically, however, much cannot be said in favor of gaseous
iron-smelting.
Some few years since considerable interest was excited by a
patent taken out by Mr. Eeece for the conversion of peat into
valuable products by a modified process of destructive distillation.
One of the subsidiary propositions involved by this patent was the
employment of the gaseous matters evolved to effect the smelting
of iron. It was hoped that the result would be equal to Swedish
charcoal wrought-iron, and that we should be rendered totally in-
dependent of that source for our supply. The process of Mr.
Eeece, however, has in no way answered the expectations enter-
tained of it. One of the most powerful incentives to the employ-
ment of gaseous combustibles has arisen in countries where
charcoal fuel is much used, — and from the consideration of the
circumstance that the mechanical conditions of powdered charcoal
render it unadapted to furnace operations. Every person who has
been accustomed to work with charcoal as fuel, even on the small-
est scale, must have experienced the loss which arises from the
pulverulent quality of that substance, and can readily imagine that
this disadvantage increases when charcoal is employed on the man-
ufacturing scale. Now the powder thus resulting, though unfit to
be employed in the condition of furnace fuel, is in the best state
of mechanical disaggregation to be converted into gas. Perhaps
the most successful apparatus for effecting the gasification of char-
coal is one used in France, and constructed on the model of an
iron-smelting furnace.
It consists of a funnel or hopper into which the powdered char-
coal is thrown, which latter sinks by its
own weight into the body of the furnace,
and is there exposed to a current of air
forced upwards through it, by a blast-pipe,
which enters the furnace underneath. If
the hopper be kept well filled with charcoal
powder, no gas will escape from its orifice ;
but the entire result of gasification will find
exit by a tuyere, and this under considera-
ble pressure. The apparatus in question is
specially designed for the combustion of
charcoal powder ; lump charcoal may how-
ever be used if the furnace or hopper be
supplied with a cover to retain the gaseous
products of combustion. Independently of
the mere question as to the advantages or
disadvantages of gaseous combustibles ab- Fi 4
stractly considered, the process of gas gen-
eration by the transmission of atmospheric air through burning
materials is attended with collateral difficulties. If care be Dot
4
50 THE PRACTICAL METAL-WORKER'S ASSISTANT.
taken to prevent the admission of more atmospherio air than is
actually required to subserve the process of slow combustion, an
explosive mixture is formed, and danger from that cause is immi-
nent. On the other hand, if the gaseous materials be allowed
to escape unconsumed, the attendant workmen are liable to be
poisoned.
NATURAL AND ARTIFICIAL BLASTS. — Next in relation to fur-
nace-heat, we have to consider the various means had recourse to
for producing atmospheric currents. These admit of division into
natural and mechanical, — the former comprehending the various
forms of chimney draughts ; the latter all those various applica-
tions of compressive means which will be presently set forth in
detail. The action of chimney draughts is immediately referable
to and dependent upon the circumstance that atmospheric air, like
all other gases and most other bodies of whatever cohesive state,
is expanded and rendered specifically lighter by heat. Thousands
of examples of this result continually present themselves, from
which we shall select a few prominent illustrations. An illustra-
tion of the diminution of specific gravity of a gaseous mixture, is
furnished by the blowing of soap-bubbles. The function of respi-
ration causes a portion of the air taken into the lungs by the act
of breathing to be robbed of its oxygen, which, by combining with
the carbon of the blood, forms carbonic acid, and is in this state
of combination expired. Seeing, then, that the air expired from
the lungs is not pure atmospheric air, but a mixture of the latter
with nitrogen, carbonic acid, and aqueous vapors, it follows that
the specific gravity of the -gaseous material expired is heavier (at
equal temperatures) than that of the unchanged atmospheric air.
Although, then, a soap-bubble, blown with warm air from the
lungs, rises, this rising cannot depend on any quality of diminished
specific gravity as a function of the gaseous matter wherewith they
are filled, inasmuch as we have seen the latter to be specifically
heavier by the amount of carbonic acid present. It depends on
the circumstance that the gaseous materials are expanded by heat,
owing their increased lightness to that cause. Hence it is that,
although for a time the bubbles ascend,
their ascension is not continuous — as would
have been the case had they been filled with
hydrogen gas — but only temporary. As
soon as their gaseous contents become
cooled to such a degree that they are spe-
cifically heavier than the external air, they
descend.
An instructive toy, demonstrating the
ascensive tendency of heated air, is rep-
_ resented in Fig.- 5. A circular disc of
Fig 5 card-board being cut, a piece of thread is
attached to the centre ; and being fixed to
a hook, the card is suspended from a fixed support. Jhus treated,
SPECIAL METALLURGY OPERATIONS. 5i
the cut card unravels, and becomes a conoidal screw helix, sus-
ceptible of rotation when an upward force is applied.
If now any small source of flame be placed underneath, the
helix will rotate, thus demonstrating the agency of an upward
force, which evidently is that of air ascending, on account of the
diminished specific gravity referable to expansion by heat. On
precisely similar principles is constructed the smoke-jack, as it is
called, — an instrument whose rotation is totally independent of
smoke, and is altogether referable to the ascensive force resulting
from the expansion of atmospheric air. Manifested in a different
way, though referable to the same primary cause, is the force
which causes the ascent of a mongolfier or fire-balloon.
Chimney-draught is a natural and very obvious consequence of
the expansion of air by heat, to which our attention has been
directed. The combustible materials cannot, as is well known,
burn without the contact of air. Part of the air concerned is sepa-
rated into its constituents, — one part of oxygen uniting with car-
bon to form carbonic acid ; another part with hydrogen to generate
water: a final portion of air remaining undecomposed, and es-
caping as it went in. Whatever the gaseous or vaporous con-
stituents which escape from burning materials may be, they are
heated by the fire to which they have been exposed, and are for
that reason expanded. Hence they have become specifically lighter,
and ascend, leaving a partial vacuum in the chimney or shaft, to be
made good by a further flow of atmospheric air, or, more properly
speaking, the gaseous results of its decomposition. A considera-
tion of the principles on which the draught of a chimney depends,
will render manifest the fact that a chimney may be too long for
the most complete activity of which a chimney is susceptible. If
it be so tall that the upward currents of air have time to cool until
its specific gravity becomes lower than the specific gravity of the
external air, or even coincident with it, the practical, no less than
the theoretical, length has been exceeded. It will be evident,
moreover, that in order to obtain the maximum heat for any given
fuel of which a furnace is susceptible, no more air should be
allowed to permeate the burning materials than the amount abso-
lutely necessary to promote the highest rate of combustion. Any
amount of passing air in excess of this theoretical quantity, what-
ever it may be, acts as a cooling agent ; and instead of augmenting
the power of combustion, diminishes it.
All furnaces which rely on mere chimney-draught for determining
the passage of atmospheric air through the materials of combus-
tion, are under the necessity of sacrificing a portion of fuel to the
object of producing the necessary flow of air ; hence for the greater
number of operations requiring a very intense heat, chimney-
draught as a means of effecting aerial transfusion is dispensed
with in favor of some form of blast. There are some purposes
however, for which the application of a blast, in the ordinary sense
of the term, would be inconvenient ; in which a chimney-draught
52 THE PRACTICAL METAL-WORKER^ ASSISTANT.
must be relied upon to some extent ; it's power being increased by
some collateral means. Iron tubular chimneys do not answer well,
because of the rapidity wherewith heat is lost through this sub-
stance, and the specific gravity of the gaseous matter which they
pour forth diminished. Nevertheless iron or at least metallic
chimneys are a necessity in the case of steam-vessels and locomo-
tive carriages. Neither one nor the other can dispense, therefore,
with a powerful draught, which is accomplished by the upward
pressure of a steam -jet.
The effect of this liberation is to drive a column of atmospheric
air violently before it, thus compensating not alone for the cooling
tendency of the materials of the chimney, but for the inadequate
height to which the chimney itself is limited by the necessities of
steam-ships and locomotive-carriages.
The pressure of steam applied as above-mentioned is very great.
Perhaps considered as a means of air propulsion, without regard
to the moisture imparted, there is no method of producing a blast
equally effective. Necessarily, however, the steam must impart
moisture to the air, thereby deteriorating the latter for all com-
bustive operations.
BLAST-MACHINES. — The most primitive method of generating
an air-blast is by some modification of the leather bellows. Orig-
inally bellows were nothing more than the skin of an animal
closely sewn except at one part, to which a spout or delivery-tube
was attached, also serving to admit a further charge of air when
the sides of the bag were pulled asunder. From this primitive
instrument to the valved single bellows, and thence to the valved
double bellows, used at this time by blacksmiths, and yielding an
uninterrupted stream, the transition is obvious. The great ad
vantages of bellows are economy of first cost, and facility of em-
ployment. They serve perfectly well for blacksmiths' forges and
small furnaces ; but the use of bellows in metallurgic operations
on the large scale is limited, and gradually decreasing.
The blowing apparatus now generally employed on the large
scale is that of compression cylinders. It is obvious that a metallic
cylinder, like the cylinder of a steam-engine, may be converted
by a simple arrangement of valves and piston work into a power-
ful apparatus for delivering compressed air. An usual form of
compression cylinder is represented in Fig. 6.
The effective power of a blowing cylinder — or, in other words,
the quantity of air of specified density which it contributes in a
given time, may be arrived at in two distinct ways. The first con-
sists in ascertaining the actual capability of the cylinder, and de-
termining the number of times it can be filled with air and the air
discharged in a given time. The second method is by ascertaining
the velocity or power of the first, determined by taking into con-
sideration the circumstances of barometric pressure, moisture, and
temperature at the time of the experiment.
As regards the former method of investigation, it must be borne
SPECIAL METALLURGY OPERATIONS. 53
in mind, that the number of times per minute, or for any other
given period, that a blowing cylinder is filled, would be a very
Fig. 6.
false criterion of the actual amount of air which finds its way into
the furnace. Owing to the elasticity of the air, ineffective space
in the cylinder, loss of air between the cylinder and piston, added
to further losses in the wind ways and regulators, the actual amount
of air which finds its way into the furnace is always some 20 or
even 25 per cent, less than the total amount subjected to compres-
sion. This loss occurs even in the best blowing cylinders. In
wooden blowing-chests — a common form of apparatus — the loss
not unfrequently amounts to nearly double. Being aware of the
loss incurred, the appended formula may prove serviceable. It
teaches the amount of air of natural atmospheric density taken
into a blowing cylinder in one minute of time.
Q =
4 d
in which
Q represents the amount of atmospheric air sought — in cubic
feet.
g the diameter of the piston in feet.
rt ratio of circumference to diameter (*". e. the number 3.1515).
h length of piston-stroke expressed in feet.
d number of revolutions expressed in terms of seconds.
Though compression-cylinders furnish the most powerful and
the most certain means of delivering air in a blast, there are others
of great practical importance. The ventilator or fan-blast is one
of the most useful, and at the same time most simple. It is repre-
THE PRACTICAL METAL-WORKERS ASSISTANT.
dented in the two following diagrams sectionally. Fig. 7 repre-
sents a cylinder or drum, cut transversely to its axis, and display-
Fig. 7.
Fig. 8.
ing the sectional view of four vanes. Fig. 8 represents the same
cylinder cut parallel to its axis, and displaying two central open-
ings, one on each side.
When the vane is put in motion, air enters by the central aper-
tures, and is forcibly and continuously driven out through the
aperture, thus constituting the blast. This form of apparatus has
been so familiarized by being substituted for domestic bellows,
that its description is almost unnecessary.
Notwithstanding the disadvantages, practical no less than theo-
retical, which attach to the employment of moist air in furnace
operations, hydraulic blasts of simple description are amongst the
most ancient; whilst modern variations on the principle of hy-
draulic blowing have given rise to some simple and curious
machines.
The trompe, as it is called, is a simple and ingenious method of
determining a current of wind by a falling current of water. It
is a form of apparatus very prevalent in Catalonia : hence the ap-
pellation "Catalan trompe," which is sometimes applied to it. The
instrument, however, slightly modified, is employed in Italy and
Switzerland, being applicable to mountainous regions where high
falls of water can be commanded, and the amount of atmospheric
pressure required is inconsiderable.
An examination of the accompanying figure will render evident
the construction and principles on which the trompe is founded.
The diagram (Fig. 9) represents a cistern above, containing
water, and communicating with the vertical pipes which respec-
tively terminate in two chests. Between these chests, and placing
them in aerial connection, is a semicircular pipe ; and the part of
SPECIAL METALLUBGIC OPERATIONS.
55
the apparatus on tine left, sectionally represented, shows a trans
verse plank, on which the water r
is broken in its fall. The action f
of the trompe is this : The verti-
cal column of water, in its de-
scent, carries before it, and min-
gled with it, considerable por-
tions of atmospheric air : striking
against the transverse plank, a
separation between the air and
water is effected, the former pass-
ing into the arched tube and es-
caping as a blast through a tubu-
lar orifice corresponding with 0,
whilst the water passes into the
lower reservoir. This form of
apparatus would be quite inopera-
tive if applied to furnaces heated
with coke or coal; but it answers
sufficiently well in cases where
charcoal is the fuel employed.
CHAIN BLAST. — This is a some-
what elaborate application of hy-
draulic laws to the purpose of
creating an air-blast. It is depicted in
gram (Fig. 10), and its con-
struction is as follows : An
endless chain, furnished with
certain appendages, the mo-
tive of which we shall pres-
ently explain, is seen to pass
over a wheel or pulley, and
through a pipe which termi-
nates in an air-chamber below.
This air-chamber communi-/".
oates with a bent tube, as rep-
resented: and a lateral tube
pointing towards the left is
also seen to be connected with
the upper part of the vertical
tubular shaft. Glancing, now,
at the transverse appendages
to the endless chain, placed at
regular intervals throughout
its length, they consist of
cylindrical boxes quite open
at one end, and capable of
being opened or shut at the
other end, each by two flaps Fig. 10.
Fig. 9.
the accompanying dia-
56
THE PRACTICAL METAL-WORKER'S ASSISTANT.
or valves. The latter fall by their own weight when the cylinders
are on the left, or. as will be hereafter seen, at every part of theii
downward descent, and open (as represented in the diagram) when
moving upwards. "When it is now explained that water enters by
the lateral orifice /, the action of the machine will be made evi-
dent. The water pressing successively on each cylinder, causes it
to descend through the vertical pipe, conveying with it the air with
which it is filled, and which cannot escape, because the valves are
shut. Each cylinder, therefore, liberates its contents of air into
the air-chamber below, and thence through the associated blast-
tube. Passing on, the valve side of each cylinder again looks
downwards, and the valves open, only to shut once more, and to
act as before described, so soon as they again take their downward
course.
A still more powerful and not less ingenious method of creating
a hydrostatic blast, is furnished by the machine known in Europe
by the name of " CagniardeUe." This instrument may be generally
described as consisting of a cylindrical screw, the shaft of which
fits air-tight to a cylinder in which it is inclosed, — the cylinder
being diagonally placed in a reservoir partially filled with water
(Fig. 11).
Fig. 11.
One end of the cylinder is seen to be flat, the other conoidal.
Through the truncated apex of the conoid a deli very -pipe is also
seen to pass ; but the diagram does- not represent what is actually
the fact, that the flat end of the cylinder is open. It follows as a
necessity of the construction of this instrument, that the atmos-
pheric air which enters by the open flat end is screwed along by
the combined force of rotation and water-pressure until it reaches
tlie tube passing through the truncated apex, which tube is a de-
livery tube for air.
EECENTLY PATENTED REFINING PROCESSES. 57
CHAPTER III.
RECENTLY PATENTED REFINING PROCESSES.
now come to deal with a class of metallurgic processes
which have recently much occupied the public attention — an at-
tention which their • importance fully justifies. 'We allude, of
course, to the processes patented or otherwise having for object
the conversion of ordinary cast-iron into malleable iron, by the
application of air, or air and steam combined, without the inter-
vention of fuel. We cannot but regret that necessity compels us
to take up the subject in its present unsettled state, as we hoped
to have communicated more exact information on these important
inventions than is at present attainable.
The processes by which iron has hitherto been converted, are
of the most laborious character ; more especially, when the gigan-
tic efforts required on the part of the workmen in the puddling
and refining processes are considered ; and it is difficult to over-
estimate the importance of any discovery by which even a portion
of this laborious operation can be dispensed with. Nor when the
economical considerations which enter into the question are borne
in mind, will it surprise the reader that the change in the iron
manufacture, which it was presumed would at once follow the an-
nouncement of Mr. Bessemer's discovery, should have created an
excitement almost amounting to a panic in the principal iron dis-
tricts. It was not in the nature of things, however, that such
startling and rapid changes should at once develop themselves in
perfection. The process, therefore, although watched with much
interest by those interested, is at present only felt to be a step in
advance of the older processes, which will be welcomely received,
should the experiments nqw preparing on a large scale fulfil the
expectations entertained of it. The inventions to which we have
alluded we shall take in their chronological order, beginning with
the earliest of them, namely :
MR. PLANT'S PROCESS. — Of this process no specification has been
published. We must, therefore, avail ourselves of the condensed
report given of it in the ;< London Journal of Arts." The patent
is dated July 18, 1849. In it the patentee claims to have made an
improvement in making bar-iron by the use of either hot or cold
blasts, with steam-jets and atmospheric air, or with steam-jets by
themselves, to be used in regulating the heat in the puddling-
chambers, either with the ordinary damper in the draught of the
chimney, or with a special damper and apparatus adapted to his
invention.
This apparatus consists of a puddling-furnace of ordinary di-
mensions, having three lines of tuyeres across the top of the fur-
nace, each line consisting of three tuyeres one inch in diameter,--
68 THE PKACTICAL METAL-WORKER'S ASSISTANT.
tlie line furthest from the chimney being for the blast, the other
two being steam-tuyeres for the puddling and preparatory cham-
bers. The blast-tuyeres are to be capable of a pressure of one
pound and upwards to the square inch ; the steam to be used at a
pressure of ten pounds and upwards.
The blast is to be introduced at the top of the puddling-chamber,
in a slanting direction, just behind the fire-bridge, so as to draw
the flame down upon the whole surface of the metal as it enters
the puddling-chamber; the steam being introduced as nearly as
possible at the same spot, and thrown in like manner upon the
whole metal.
By these means, it is stated, the heat of the furnace and pre-
paratory-chambers can be regulated with great nicety, without em-
ploying the damper usually inserted in the chimney of a puddling-
furnace. When the metal is melted, the blast is shut off, and steam
introduced through the tuyeres until the iron boils ; the steam is
then turned off and the blast brought into action till the iron ap-
pears above the cinder, when the blast is again shut off and the
iron finished in the usual manner by the ordinary draught. The
heat of the puddling-chamber is raised or lowered from time to
time by raising or lowering the damper over the fire-bridge.
In this process, a greater separation of the metal is caused, it is
presumed, by the blast of air and jets of steam thrown upon the
metal; and the carbon and other impurities are supposed to be
more thoroughly removed by the infusion of the oxygen of the
atmosphere.
MARTIEN'S PROCESS, to which we shall now call attention, is that
patented by Joseph Gillot Martien, of Newark, New Jersey, in
September, 1855, and has for its object the purification of iron when
in the molten state from the blast or refining-furnace, either by air
or steam, or vapor of water applied from below, so that it may
rise up amongst, and completely penetrate and search every part
of the metal previous to congelation, and prior to its being run
into a reverberatory-furnace for puddling. By this means the
manufacture of wrought-iron by puddling, and the manufacture of
steel from cast-iron in the ordinary manner, are stated to be greatly
improved.
In carrying out his invention, Mr. Martien employs channels, or
gutters, so arranged that the numerous streams of air, of steam, or
of vapor of water, are passed through and amongst the melted
metal, as it flows from the blast-furnace. This is done by subjecting
the metal to the action of streams of air or steam, as it passes from
the blast-furnace before it congeals. The apparatus recommended,
consists of cast-iron channels or gutters, having the bottom made
hollow to receive steam or air, or both. This gutter is perforated
with numerous holes, obliquely inclined in the direction of the
flowing metal, so that the streams of air or steam may be forced
through it as it flows along the gutter. The stream of air, however,
may also be passed up through the metal ; or the holes may be in-
RECENTLY PATENTED REFINING PROCESSES. 59
dined in the opposite direction, so as to oppose the flow of the
molten metal. When the hot or cold-blast is used, the hollow
bottom of the gutter may be connected with the air-pipes used for
supplying the blast ; or, when steam is employed, the gutter may
be connected with the boiler. By these means, the air or steam in-
troduced rises up through the metal in numerous streams, and the
iron is stated to be perfectly purified after it has come from the
blast-furnace, and before congelation takes place. The iron thus
purified may be allowed to cool in the mould, or it may run from
the gutter into a reverberatory or other refining furnace, to be
heated and puddled in the usual manner. In this process, the
novelty claimed is that of purifying iron from a blast-furnace while
still in a molten state, without the intervention of fuel ; thus pre-
paring it for the puddling process in a state of greater perfection
than by the old process. The perceptive faculties of James
Nasmyth, to use the words of Mr. Bridges Adams, the eminent
civil engineer, "detected the absurdity of setting a number of
human beings to stir up a metallic puddling in order to throw pff
the scum in the shape of slag or cinder. His remedy was a me-
chanical one — to cause the mass to boil like a pot, by forcing steam
into it from below, the issue of steam beginning before the molten
mass was poured in, so as to insure against the stoppage of the
passages. But steam is not exactly fuel, and, instead of increasing,
tends to lower the temperature of the mass of iron."
MR. CLAY'S PROCESS. — Among other ingenious inventions, we
may here mention that of Mr. Clay of the Mersey Iron Works, — an
invention for which a patent was taken out and a specification lodged,
as applicable both to malleable iron and cast steel ; although all
claim for the latter purpose has since been withdrawn in favor of
Captain Uchatius's process. Mr. Clay proposes to refine the crude
iron by a process of granulation, produced by dropping iron in a
molten state from a lofty tower into a water-tank, after the manner
in which small lead-shot is cast. In this process, he states that the
highly separated metal is purified by contact with the air in its
lengthened descent, and by the chemical change produced by im-
mersion in the water, so that, when again melted for the puddling
furnace, it is divested of most of the impurities of crude iron.
For the purposes of this invention, iron may be obtained either
from the blast-furnace, from which it may be run out in a molten
state, or it may be melted down from pig or scrap cast-iron. The
granulation of the iron is effected by causing the metal, when in a
molten state, to run through a perforated plate of metal or other
material, placed at the top of a tower-shaft or well ; by this means
it will be divided into small shot-like particles. In its descent in
this state from a suitable height, varying according to the nature
and quality of the iron operated upon, the metal will, during its
passage through the air, be partially decarbonized, inasmuch as the
oxygen of ordinary atmospheric air acts with considerable force in
decarbonizing the metal as it falls through it ; it will thus be ren-
60 THE PRACTICAL METAL-WORKER'S ASSISTANT.
dered more suitable for working up by puddling into malleable
bar-iron.
It is sometimes advisable to charge the air in the shaft, through
which the molten metal is to pass, with artificially prepared oxygen,
or with some other decarbonizing gas or vapor, which will produce
a more vigorous decarbonizing action upon the iron. This may
be effected by the decomposition of the salts of potash, such as
chlorate of potash, or nitrate of potash, both of which contain con-
siderable quantities of oxygen; and their decomposition may be
effected either by dropping the red-hot metal, in a granulated or
finely-divided state, upon a bed of the salts of potash, or by heating
the salts in a retort until oxygen is given out. Other minerals,
also, such as manganese, may be employed, either alone or in com-
bination with other substances, as oxygenating agents. The pat-
entee also employs the more simple means of increasing the
oxygenizing powers of atmospheric air, by introducing a blast or
draught of air, either hot or cold, as may be found most effective,
into the tower down which the iron is descending. Dry steam may
also be applied to effect the object in view.
Mr. Clay has found that by allowing the molten metal to fall
through the air a distance of about seventy feet, a satisfactory result
has been obtained ; this, however, depends both upon the quality
of the iron and upon the state of preparation in the shaft. With at-
mospheric air at the ordinary pressure, the metal requires to fall
through a greater distance, than if charged with the artificial means
above referred to. The granulated particles of molten iron may
either fall into water at the bottom of the tower or well, or they
may be collected in a vessel or reservoir placed for the purpose.
The decarbonized metal thus obtained, it is scarcely necessary
to add, is collected together and remelted into ingots or bars, pre-
paratory to undergoing the ordinary treatment of hammering and
rolling.
MR. BESSEMER'S PROCESS. — We have now to speak of that pro-
cess of Mr. Bessemer's, which has arrested so much attention, even
of the ordinary reader, in the last few months. Mr. Bessemer's first
patent is dated January 4, 1856. Others he has since taken out
bearing date February 12, May 15 and 31, 1856. To the most com-
plete of these, namely, that of February 12, 1856, we shall direct
our attention. In the specification now before us the invention
is said to consist in the decarboirization and refinement, in whole
or part, of the crude iron, which is either obtained in a fluid state
from the furnaces in which the iron ore has been reduced, or in the
decarbonization and refinement of crude pig or finery iron, by re-
melting the pigs in a suitable furnace so as to obtain fluid metal
capable of being treated by the process we are about to describe.
This consists, firstly, in running the fluid iron from the furnace
into a close or nearly close vessel or chamber, formed of iron, per-
forated with openings to receive the tuyeres, and lined with fire-
brick or other material which is a slow conductor of heat. When
KECENTLY PATENTED EEFINIXG PKOCESSES. 61
this vessel is almost half filled, numerous small jets of atmospheric
air, or gaseous matter capable of evolving sufficient oxygen to
cause combustion of the carbon of the iron, are forced into and
among the fluid metal, either in a cold or previously heated state.
" Atmospheric air or oxygen is thus introduced into the metal, in
sufficient quantities to produce a vivid combustion among the
particles of the fluid metal; and to retain and increase its temperature
to such a degree, that the metal will continue fluid during its
transition state from crude iron to that of cast steel or malleable
iron without the application of fuel."
Mr. Bessemer stated in the paper with which he ushered his in
vention to the British Association, that for the last two years his
attention had been almost exclusively directed to the manufacture
of malleable iron and steel, in which, however, he had made but
little progress until within the last eight or nine months. The
constant pulling down and rebuilding of furnaces, and the toil of
daily experiments with large charges of iron, had already begun
to exhaust his stock of patience ; but the numerous observations
made during this very unpromising period all tended to confirm an
entirely new view of the subject, which at that time forced itself
upon his attention — viz., that he could produce a much more intense
heat without any furnace or fuel, than could be obtained by either
of the modifications hitherto used, and consequently not only avoid
the injurious action of mineral fuel on the iron under operation,
but at the same time avoid the expense of the fuel. Some prelim-
inary trials were made on from 10 Ib. to 20 Ib. of iron, and, although
the process was fraught with considerable difficulty, it exhibited
such unmistakable signs of success as to induce him at once to put
up an "apparatus capable of converting about 7 cwt. of crude pig-
iron into malleable iron in thirty minutes. With such masses of
metal to operate on, the difficulties which beset the smaller experi-
ments entirely disappeared. On this new field of inquiry, he set
out with the assumption that crude iron contains about five per
cent, of carbon ; that carbon cannot exist at a white heat in the
presence of oxygen without uniting therewith and producing com-
bustion ; that such combustion would proceed with a rapidity de-
pendent on the amount of surface of carbon exposed : and, lastly,
that the temperature which the metal would thus acquire, would be
also dependent on the rapidity with which the oxygen and carbon
were made to combine, and consequently that it was only necessary
to bring the oxygen and carbon together in such a manner that a
vast surface should be exposed to their mutual action, in order to
produce a temperature hitherto unattainable in our largest furnaces.
With a view of testing practically this theory, he constructed a
cylindrical vessel of three feet in diameter and five feet in height,
somewhat like an ordinary cupola furnace, the interior of which
was lined with fire-bricks, and at about two inches from the bottom
of it five tuyere-pipes were inserted, the nozzles of which were
formed of well- burnt fire-clay, the orifice of each tuyere being
62
THE PRACTICAL METAL-WORKER S ASSISTANT.
about three-eighths of an inch in diameter ; they were so put into
the bricklining (from the outer side) as to admit of their removal
and renewal in a few minutes when they were worn out. At one
side of the vessel, about half way up from the bottom, there is a
hole made for running in the crude metal ; and on the opposite side
there is a tap-hole stopped with loam, by means of which the iron
is run out at the end of the process.
The apparatus by which it is now proposed to carry out this
process, differs somewhat from that described above : it is a cylin-
drical vessel, mounted on axes not placed at the centre of gravity.
Of this vessel, Fig. 12 is an end elevation. The vessel is formed of
Fig. 12.
stout plates, secured by angular iron flanges to the cast-iron plates a',
strengthened by webs or ribs of iron, c c are iron frames secured
by bolts d to the masonry, or foundation on which the operation
rests. The frame cf rises higher than the others, and has plummer
blocks e e bolted to it, on which the shaft / revolves. A worm-
wheel g is keyed firmly on to the axis b, and receives motion from
the worm h when moved by the handle i. At the point of junc-
tion of two of the webs a, will be seen a boss ; into this boss a
stud is fixed, to which a chain, or tension-rod, may be attached,
suspended over a pulley from the roof, for supporting a counter-
balance weight, so as to facilitate the movement of the vessel on
its axis, and assist the worm-wheel gearing g h..
RECENTLY PATENTED REFINING PROCESSES.
63
The intention in having the refining vessel thus mounted on
n,xes, is the convenience it offers for pouring out the fluid metal
into the ingot-mould, for which purpose it is furnished with a lip
or spout, which is placed in a line with the mould, the latter being
kept in a proper position for removing the fluid contents. The
air, or other gaseous matters, which are to operate on the metal,
must be compressed with a force greater than will balance the
weight of a column of fluid metal of a height equal to the depth
of immersion of the jets below the surface of the fluid metal.
This air, as will afterwards be shown, is introduced at the sides or
ends of the vessel, through small holes formed in the fire-clay
lining ; so that, by moving the chamber on its axis, the holes in
the fire-clay may be made to descend beneath the surface of the
metal, or raised above it as may be desired.
In Fig. 13 is represented a longitudinal section of the converting
vessel, in order to give a more correct idea of its construction.
Fig. 13.
The section presents, at one side of a! and at a point beyond the
outer edges, the bosses a', which are bored out truly, and fitted and
keyed to the axes b b ; and on these the vessel is made to move
when turned by the worm-gearing g h (Fig. 12). At r there is a
pipe which communicates either with a blast-engine or steam-
boiler, or it may be made to communicate with a reservoir of
oxygen gas, or any other gaseous matter capable of evolving oxy-
gen, either in a cold or heated state. The pipe r is fitted to one
end of the trunnion or axis b, which is hollow, and provided with
a stuffing-box, or other joint, so as to allow of the movement of
the axis without interfering with the passage of the air or other
matters through it. This pipe is continued to S, and along the
outside of the vessel S, where it requires to be turned truly on its
exterior surface, having fitted to it several small branch-pipes it,
THE PRACTICAL METAL-WORKER'S ASSISTANT.
each of which has a T piece connected to it, which is bored out
truly, so as accurately to fit the exterior of the pipe S ; thus ad-
mitting of the pipe u being moved on the pipe S into its proper
position. The object here, is to connect the blast-engine with the
converting vessel, along one side of which there is a row of square
holes : into these, small blocks of well-burnt fire-clay are closely
fitted, and held in position by ramming a little loam into the joint
formed between them and the lining m. At one of these blocks
or tuyeres, the pipe u is fitted by a simple cone joint, the other
ends of the tuyere-blocks having several small perforations leading
into one larger passage communicating with the pipes u ; a com-
munication is thus established between numerous points of the
interior surface of the converting vessel and the blast-engine or
other apparatus used. A sluice-cock on the pipe r, enables the
workman to turn this off or on as required.
The manner in which these pipes and tuyeres act will be better
understood by the following engravings, where Fig. 14 represents
a section of the pipe
u, and the mode of
fitting it into the
pipe S ; while Fig. 15
shows them in their
ordinary working po-
sition. It will be seen
by Fig. 14 that the
pipe S has an open-
ing at x opposite the
orifice of the pipe u.
When these pipes oc-
cupy their ordinary
position, as in Fig,
15, the air passes
freely through the
opening ; but when
the tuyere-blocks require renewing, the pipe u can be turned upon
the union joint formed at the junction x : free access to the tuyere
is thus obtained. The manner in which these pipes act upon the
metal in the converting vessel is shown in Fig. 16, and again in
Fig. 17.
The tuyere-blocks may be formed of one or of several smaller
apertures, one being found to answer perfectly well in practice ;
they must, however, be made to fit exactly into the pipe. These
passages sometimes get obstructed. To provide for this, a screw-
plug (Fig. 14) is fitted at the back of the elbow of the pipe u,
which maybe removed if necessary, and a steel rod thrust through
the aperture, so as to remove any accumulations of matter.
The interior of the converting vessel itself is lined with fire-
brick or fire-stone, as shown at m (Fig. 13) ; and arrangements are
made by which this lining may be renewed or repaired either by
Fig. 14.
Fig. 15.
tvECENTLY rATENTED REFINING PROCESSES.
removing one of the *,nd plates a', which can be bolted en again :
or a man - hole
may be devised
in the side of the
vessel through
which the lining
may be repaired
without this re-
moval. The pe-
culiarities of the
vessel itself we
shall now de-
scribe ; and in
order to convey
a correct idea of
it, we give two il-
lustrations (Figs.
16 and 17): one
a vertical sec-
tion, exhibiting the vessel while the metal is in a molten state,
Fig. 17.
with the tuyeres in full operation; the other, a similar ./ee
tion, where the fluid metal is presumed to be purified, and in
5
66 THE PRACTICAL METAL-WORKER'S ASSISTANT.
the act of being poured out into the moulds and formed into
ingots. In each of these sections the peculiar lip-like form
of the spout n of the vessel is shown. This projecting spout
is for the purpose of running out the fluid metal, and is
made to project from the vessel so far as to bring it in a line
with the axis, so that into whatever position the vessel a may
be moved, the extremity of the lip n may retain the same position,
or nearly so ; thus allowing the stream of metal flowing over it to
fall into the ingot-mould. By reference to Fig. 17 it will be seen
that at mf the lining is formed so as to prevent the slag and other
impurities floating on the surface from flowing out until after the
'metal itself has run out. On each side of the spout n there is a
curved passage £>(Fig. 16), by means of which the flame and gaseous
products evolved during the process may escape ; but the plashes
of metal thrown up by jets of air are, for the most part, prevented
from escaping by the serpentine form of these outlets in the con-
verting vessel.
Having thus minutely described this apparatus, let us follow its
author through the process. When the chamber is about half-filled
with fluid metal drawn from a smelting or remelting furnace, atmos-
pheric air, either in a cold or heated state, or gaseous products capable
of evolving combustion of the carbon contained in the iron, is blown
or forced into and among the fluid metal ; and this is found suf-
ficient to keep up the required temperature during the process.
The size and number of jets or tuyere-pipes required for this
purpose vary according to the quantity of metal operated upon
at a time, and also with the condition and quality of the metal ;
thus forge, pig, or refined plate metal, will not require so much
oxygen to complete its carbonization and conversion into malleable
iron, as is required for the conversion of cru$e iron of the quality
known as No. 1 or No. 2 foundry-iron. To these qualities of
metal a tuyere is required having an outlet larger by about twenty
per cent, than is used for the white qualities of iron. The patentee
hesitates, however, in giving any fixed rule where so much de-
pends upon the force or pressure of the blast and the quality of
the iron, preferring to give the following example from his own
practice as a guide to the workmen. " When using foundry-iron
of the quality No. 2," he says, " I run one ton into the converting
vessel, in which it rises to the height of about a foot above the
orifices of the tuyere pipes ; and then force into the fluid metal,
atmospheric air in its natural state, under a pressure of about ten
pounds to the square inch, employing from six to twelve tuyere-
pipes for its distribution, the united area of the pipes being two
square inches. The quantity of blast admitted by this area of
inlet, will in general be found sufficient to effect the conversion of
the crude iron into a malleable condition in about thirty minutes.
Where a mixture of oxygen gas with atmospheric air or steam, or
steam alone ; or where other gaseous fluids capable of evolving
oxygen are preferred in lieu of atmospheric air ; then the size of
RECENTLY PATENTED REFINING PROCESSES. 67
the tuyere-pipes should be regulated according to the quantity of
oxygen present, diminishing the area of the pipes where the oxy-
gen is in excess, and increasing the area where the quantity is
short of the above proportion."
When the vessel is new, or newly lined, it may be heated by
the waste gases of the blast-furnaces, or any other convenient
means, previous to the crude iron being poured in. The patentee
sums up the substance of his discovery in the following terms :
" It is well known that molten crude iron, under ordinary circum-
stances, will soon become solidified unless a powerful fire is kept
up, and is applied direct to the fluid metal, or to the exterior of
the vessel containing it. It is also well known that if the quantity
of carbon which is usually associated with crude iron is dimin-
ished, that the temperature necessary to maintain its fluidity also
rises in like manner, so that when iron has lost the whole or the
greater part of its combined carbon, the metal can only be kept in
a fluid state by the heat of powerful furnaces. But I have dis-
covered that if atmospheric air or oxygen is introduced into the
metal in sufficient quantities, it will produce a vivid combustion
among the particles of fluid metal, and retain and increase its tem-
perature to such a degree that the metal will continue fluid during
its transition from crude iron to the shape of cast-steel or mallea-
ble iron without the application of fuel, the high temperature
being obtained by the oxygen uniting with and causing a com-
bustion of the carbon in the crude iron, and by the combustion of
small portions of the iron itself."
As a matter of convenience, the patentee suggests, while re-
serving his right to apply modifications of the apparatus described,
that the converting vessel should be placed near to the discharge-
hole of the blast or remelting furnace, from which the crude iron
is to be drawn ; that the interior of the chamber should be heated
by burning gases, or by introducing wood-charcoal or coke at the
passages p (Fig. 16) ; and that a blast of air be turned on through
the tuyere-pipes, by which their combustion may be kept up and
the vessel dried before turning the crude metal into it. For this
operation the vessel is placed in the position shown by Fig. 16,
having a movable gutter leading from the tap-hole of the smelting
furnace into the upper end of one of the passages p, the tuyere-
pipes being now in operation. As soon as the metal covers the
orifices of the tuyere-blocks, a violent ebullition is produced, the
air dividing into globules, and diffusing itself among the particles
of fluid iron, and thus coming in contact at numerous points with
the carbon consumed in the crude iron, and producing thereby a
vivid combustion, while the gaseous products escape by the pas-
sages p.
In about fifteen minutes from the time of commencing the pro •
cess,"' large frothy slags are thrown violently out of the passages p,
accompanied by a rush of bright flame. After a few minutes'
duration this eruption ceases, but copious flame still continues to
68 THE PRACTICAL METAL-WORKER'S ASSISTANT.
escape by the passages. At this stage of the process the crude
metal has thrown off the bulk of its impurities, and is, in all prob-
ability, in the state of cast-steel ; its exact state, however, can be
ascertained by turning the handle-shaft / so as to bring the vessel
round on its axis, as in Fig. 17, when a portion of the metal may
be discharged into an ingot-mould, where it is quickly cooled and
examined. If not sufficiently decarbonized, the vessel is restored
to its original position, and the process continued until completed,
— from five to ten minutes' blowing being generally found sufficient
to convert the metal from the condition of cast-steel to malleable
iron. When it is necessary to suspend the operation of blowing
for a short time, the vessel should be brought into a position half-
way between Figs. 16 and 17, so that the orifice of the tuyere-
pipes maybe above the surface of the metal, otherwise the tuyeres
will be stopped up with the fluid metal. The whole process of
conversion from crude pig-iron No. 1 to malleable iron, occupies
from thirty to thirty-five minutes, varying according to the quality
of the pig ; but the exact point when the process should cease,
will soon be acquired by the workmen, since the color and volume
of the flame issuing from the passages vary with the condition
of the metal, thus forming a good guide for the workmen ; while
the facility with which trial-ingots may be taken affords an in-
fallible test.
The heat, in some cases, is so excessive that the metal, even
when reduced to malleable iron, is still so far above the melting
point that its temperature requires to be reduced before casting.
For this purpose, the vessel is brought into the position half-way
between that shown in Figs. 16 and 17, the tuyeres being above
the surface of the metal, the supply of air stopped, and a fire-brick
placed over the orifice of the passage p, so as to prevent the heat
from escaping with too much rapidity. In this way the tempera-
ture gradually subsides, and the metal is brought into a proper
state for casting ; or, if that is preferred, for taking out of the ves-
sel in masses after cooling down by stirring.
We have now to deal with a part of the refining process in
which it occurs to us that Mr. Bessemer has been altogether mis-
understood, both by those who have criticised his inventions most;
severely, and by the general public. The notion generally enter-
tained, we believe, is that by means of combustion alone, and with-
out fuel, that gentleman professes to produce malleable iron. This
is not so. He only professes to have discovered, that the rapid
union of carbon and oxygen which takes place at the temperature
which has now been attained, still further increases the tempera-
ture of the metal, while the diminished quantity of carbon present
allows a part of the oxygen to combine with the iron, which un-
dergoes combustion, and is converted into an oxide.
At the excessive temperature which the metal has now acquired,
lie continues, the oxide undergoes fusion, and forms a powerful
solvent of those earthy bases that are associated with the iron
RECENTLY PATENTED REFINING PROCESSES.
69
The violent ebullition which is going on mixes most intimately
the scoria and metal, every part of which is thus brought in con-
tact with the fluid oxide, which will thus wash and cleanse the
metal most thoroughly from the silica and other earthy bases which
are combined with the crude iron, while the sulphur and other
volatile matters which cling so tenaciously to iron at ordinary tem-
peratures are driven off, the sulphur combining with the oxygen
and forming sulphurous acid gas, — producing by this means a
purer iron by the application of atmospheric air to the fluid metal
than could be produced in the puddling-furnace by a large con-
sumption of that costly material. Beyond that, the process recom-
mended very much resembles the mechanical appliances by which
malleable iron is produced by the older methods : namely, by sub-
jecting the ingots at a welding heat to a forge-harnmer or squeezer
of a peculiarly powerful construction.
During the interval occupied in cooling down the boiling metal,
the workman has to prepare his ingot-moulds. A convenient
mode of doing this is to place them in an iron truck, mounted on
wheels, which may be moved under the spout of the vessel, and
passed out under the arched openings left in the furnace. The
ingots thus prepared, are now in a fit state for being hammered,
tilted, or rolled into bars, rods, 'or plates. In some cases the ingots
are found to contain cells and cavities ; in this case they are sub •
jected at a welding heat to the action of squeezers, or they are
subjected, in a suage or die, to repeated blows under a powerful
hammer, so that the parts are forcibly driven together, and the
cells welded before being subjected to the rolling-mill or tilt-
hammer.
The squeezers, and other apparatus recommended by Mr. Besse-
mer, differ considerably from those generally in use. The squeezer
has transverse grooves, both on the upper and lower jaws, as repre-
sented in 'Fig. 18: A A being the grooves or hollows, B an ingot
Fig. 18.
placed between the jaws. In this operation the ingot, or mass of
metal, is brought to such a temperature in a suitable furnace as
70
THE PRACTICAL METAL-WORKERS ASSISTANT.
will sufficiently soften it to admit of its being pressed into a solid
homogeneous body.
The same effect may be produced by hammering the ingot on a
suage or die, as illustrated in Fig. 19, where P represents the lowei
portion of a steam-hammer, having a grooved
block Q fitted into it ; a similar block N is se-
cured to a heavy mass of metal 0, which forms
the bed of the hammer; M being awrought-iron
hoop, lined with steel, which is made so as to
slide up or down by means of the rods S. The
workman, having heated the ingot G, holds' it
with a pair of tongs in the groove of the lower
block, while the upper one falls upon it with
such force as is necessary. By the use of these
grooved surfaces, or suages, the ingot of metal
Fig. 19. is less liable to be crushed than when ham-
mered between two parallel flat surfaces, which give no support
to its sides. In this operation the work-
man will move the ingot backwards and
forwards, turn it over on its side, and
so work and compress the metal while
at a welding heat, as thoroughly to
solidify the iron and render it fit for
the tilt hammer or rolling-mill.
Fig. 20.
Other modifications of the steam-hammer are mentioned by
Mr. Bessemer, all however having one principle, viz., that the ingot
is placed upon a block or anvil, supported on both sides by strong
rests, while the hammer falls into the groove formed by these sup-
ports. By this means the tendency of the ingots to crush out lat-
erally is prevented, while the metal is left at liberty to expand itself
in length, thus undoubtedly encouraging the fibrous condition insep-
arable from malleable iron. This effect is produced by many
modifications of apparatus, the details of which are unimportant,
provided the dies or suages are so constructed, and the ingot of
spongy or cellular metal so confined, that when the hammer is
brought forcibly in contact with it the tendency is to have its
various parts forcibly squeezed, pressed, or driven together, the
pores closed, and the surfaces united or welded together.
In the probationary state of these patented processes it is im-
possible to draw any decided conclusions as to their probable re-
sults. There is that in Mr. Bessemer's process which has strongly
impressed the public mind, and which only the conviction of com-
plete success or failure will satisfy. "While the popular view has
thus, sometimes with little knowledge of the subject, magnified the
discovery far beyond its merits, there have not been wanting others
who would divest it of any merit whatever, and treat it as alto-
gether unworthy of serious consideration. As in most other cases,
truth seems to lie between these extremes.
We have already seen that the principal impurities in cast-iron
RECENTLY PATENTED REFINING PROCESSES. 71
consist of carbon, sulphur, phosphorus, silicon, and some other
substances of less importance. These substances, Mr. Bessemer
asserts, combine with oxygen at a high temperature, forming vola-
tile compounds, which are incapable of again entering into com-
bination with the metal. The principle of Mr. Besseiner's process
is to take advantage of this tendency of the substances to unite
with oxygen. By forcing atmospheric air into the fluid metal, in-
tense combustion is produced ; the volatile gases unite with the
oxygen, and disappear through the channels prepared for their
exit. This, say some of the objectors, is unsound in theory — that
practically neither sulphur nor phosphorus, the two substances
most injurious to iron, are separated by the process.
In support of these views, a writer in the " Birmingham Jour-
nal," to whom we are indebted for some excellent remarks on this
process, some of which have been imported into these pages, thus
reiterates his objections. Eecurring to objections formerly urged
against the process in the pages of the same journal, the writer
says :
" Especially important too, is it, that accurate chemical analysis
should be resorted to, to show the composition of this iron, and to
prove that the new process will truly purge it of sulphur and
phosphorus, as we understand Mr. Bessemer to say it will — ele-
ments, the presence of one per cent, of which is fatal to the quality
of the iron.
" So far as we are aware, this important information has not been
communicated to the public ; and so long a time has now elapsed
that we despair of receiving it from the quarter it was most natu-
rally expected from. In the hope of contributing to the settle-
ment of a question which has already too long disturbed the
public mind, we have imposed upon ourselves a task which we
think should have been spared us, and present to our readers such
an analysis of Mr. Bessemer's iron as we have been daily hoping
to see published by that gentleman himself. The specimen we
have experimented upon possesses those physical properties which,
from repeated descriptions, the public are sufficiently familiar with.
The iron consists of an agglutinated mass of large brilliant crys-
talline grains, possessed of a very imperfect malleability ; flatten-
ing under the blow of a hammer ; but almost invariably cracking
at the edges. It is wholly destitute of a fibrous structure, and only
after having been repeatedly heated and drawn out in a smith's
forge, exhibits the properties of an inferior wrought iron. On
analysis it was found to have the following composition :
Iron 98-9
Phosphorus 1'08
Sulphur 016
Carbon O05
Silicon traces
100-12
72 THE PRACTICAL METAL-WORKER'S ASS^STA^T.
" This composition is so accordant with the physical prope. tier
of iron, that, the composition being given, the chemist "vould have?
no difficulty in predicating its more marked characteristics. Its
crystalline structure and fusibility are very satisfactorily accounted
for. In order more exactly to illustrate the nature of the change
effected by Mr. Bessemer 's treatment, we append an analysis of
refined iron produced at a large establishment in the neighborhood
of Birmingham. We are indebted to the courtesy of Dr. Percy
for this analysis. It was made in his laboratory by one of his
assistants, Mr. Dick. The iron was obtained only a few months
ago, and may be regarded as representing the average composition
of refined iron as made at the present moment in this neighbor
hood :
Iron 95-14
Carbon (combined) 3*07
Phosphorus 0-734
Silicon 0-63
Sulphur 0*157
Manganese trace
Kesidue, insoluble in hydrochloric acid . 0*53
100-261
The residue, insoluble in hydrochloric acid, yielded :
Silica . . . . 0-3
Alumina, with a little peroxide of iron . . 0'14
0-44
" In contrasting the change effected by Mr. Bessemer's treatment
with that of the refinery, the following particulars force themselves
strongly upon our notice. Mr. Bessemer's method removes most
effectually the carbon and silicon, while in the refinery these are
but little diminished. The carbon is eliminated with a perfection
which we should scarcely have thought possible, but we are with-
out information as to the sacrifice at which this has been effected.
The amount of iron oxidized by the vivid combustion which
Mr. Bessemer induces, we are unable to ascertain. The point
which most prominently strikes the chemist in Mr. Bessemer's
iron, is the large amount of phosphorus which it contains — an
amount utterly fatal, we fear, to the value of Mr. Bessemer's
method. His treatment, we suspect, does not sensibly diminish the
amount of this element ; but this, too, is a point on which we must
be dependent on Mr. Bessemer. We have had no opportunity of
examining the slag produced in the treatment ; but we learn from
an eminent chemical authority, that at least one sample of it con-
tains no sensible amount of phosphoric acid. We have previously
explained that it is by the puddling process that the phosphorus
and sulphur are mainly removed ; the chemical examination of the
tap-cinder of the puddling furnace disclosing an abundance of
phosphoric acid. As yet, so far as we can learn, Mr. Bessemer has
RECENTLY PATENTED REFINING PROCESSES. 73
f > , i;
done nothing towards the removal of this pernicious element, _
phorus ; and in this important respect his process must , be re- (j
garded as a failure." '* ^ \ V
We have elsewhere incidentally alluded to the strange oversight}
committed by the objectors to Mr. Bessemer's process — all allusion ^^
to his hammering and squeezing processes are invariable suppressed ;
consequently certain magical results are expected, to which, as it
appears to us, he does not lay claim. On the contrary, his specifi-
cation distinctly claims the peculiar squeezing and hammering
process already described ; lateral compression and elongated fibrous
expansion being the results sought for. It is true, he only mentions
this portion of his improvements incidentally, when he claims for
the new process facilities for forming large masses of iron capable
of producing bars that could not have been obtained by the old
process by means of powerful machinery not yet matured, whereby
great labor will be saved and the operation greatly expedited. It
is obvious, therefore, that great importance is attached by the pat-
entee to the subsequent operations. Nevertheless, with all our
desire to see Mr. Bessemer's process crowned with success, we can-
not avoid seeing that it has yet much to overcome. Early in Oc-
tober, Mr. Bessemer sent ingots of his pneumatically refined iron
to the Dowlais iron- works, where it was operated upon, the result
being a fair-faced iron, equal, apparently, on the outer surface, to
any ever rolled. It stood the lever or dead test well ; but the sharp
blow of the ram, and the sharp squeeze of the eccentric straightener,
it could not bear, for which its steely or crystalline structure prob-
ably accounts. Practical men observed, that along the surface of
the rail a stratum of fibrous iron — evidently the result of elongation
through the rolls — presented itself; and this was considered great
encouragement for Mr. Bessemer to prosecute his idea to perfection.
In reference to this railway bar, Mr. Bessemer states, that it was>
rolled direct from a ten-inch square ingot, having passed through
the rolls fourteen times. The metal was not previously piled or in
any way wrought ; but, notwithstanding the extremely difficult sec-
tion, not the smallest portion of the flange was torn up. To render
the fabrication of the same form of rail practicable on the old plan,
twice-rolled iron is used to form the flange, and ten shillings per
ton extra is being paid for it in consequence.
The process is stated to have been successfully applied to the
manufacture of iron for tin-plating. The best puddle-iron has
heretofore failed to produce the requisite toughness, and charcoal-
smelted iron has in consequence been used for this purpose at a
considerable extra cost per ton ; but we have examined sheets
rolled from ingots prepared by the new process, remarkable for
their thinness, and affording proofs of the great ductility and tough-
ness of its product.
We have also inspected, as instances of the extreme tenacity
capable of being produced by this process, rolled out metal of such
extreme thinness and pliability as to bear, when annealed, a close
74 THE PRACTICAL METAL-WORKERS ASSISTANT.
resemblance in fabric to paper, with much greater toughness and
tenacity.
"We shall conclude these remarks by quoting the concluding
portion of Mr. Bessemer's address to the British Association : —
" One of the most important facts," he says, " connected with the
new system of manufacturing malleable iron is, that all the iron so
produced will be of that quality known as charcoal iron ; not that
any charcoal is used in its manufacture, but because the whole of
the processes following the smelting of it are conducted entirely
without contact with, or the use of, mineral fuel. The iron result-
ing therefrom will, in consequence, be perfectly free from those in-
jurious properties which that description of fuel never fails to
impart to iron that is brought under its influence. At the same
time, this system of manufacturing malleable iron offers extraordi-
nary facility for making large shafts, cranks, and other heavy
masses ; it will be obvious that any weight of metal that can be
founded in ordinary cast-iron by the means at present at our dis-
posal may also be founded in molten malleable-iron, and be wrought
into the forms and shapes required, provided that we increase the
size and power of our machinery to the extent necessary to deal
with such large masses of metal. A few minutes' reflection will
show the great anomaly presented by the scale on which the con
secutive processes of iron-making are at present carried on. The
little furnaces originally used for smelting ore, have from time to
time increased in size, until they have assumed colossal proportions,
and are made to operate on 200 or 300 tons of materials at a time,
giving out ten tons of fluid metal at a single run. The manufac-
turer has thus gone on increasing the size of his smelting furnaces,
and adapting to their use the blast apparatus of the requisite pro-
portions, and has, by this means, lessened the cost of production in
every way ; his large furnaces require a great deal less labor to
produce a given weight of iron, than would have been required to
produce it with a dozen furnaces ; and in like manner he dimin-
ishes his cost of fuel, blast, and repairs, while he insures a uniform-
ity in the result that never could have been arrived at by the use
of a multiplicity of small furnaces. While the manufacturer has
shown himself fully alive to these advantages, he has still been
under the necessity of leaving the succeeding operations to be
carried out on a scale wholly at variance with the principles he
has found so advantageous in the smelting department. It is true
that hitherto no better method was known than the puddling pro-
cess, in which from 400 to 500 weight of iron is all that can be
operated upon at a time, and even this small quantity is divided
into homoeopathic doses of some TOlbs. or 801bs.,each of which is
moulded and fashioned by human labor, carefully watched and
tended in the furnace, and removed therefrom one at a time, to be
carefully manipulated and squeezed into form. When we consider
, the vast extent of the manufacture, and the gigantic scale on which
the early stages of the progress are conducted, it is astonishing
REFINING AND WORKING OF IROIS. 75
that no effort should have been made to raise the after processes
somewhat nearer to a level commensurate with the preceding ones,
and thus rescue the trade from the trammels which have so long
surrounded it."
CHAPTER IV.
REFINING AND WORKING OF IRON.
THE iron furnaces of the United States are, generally speaking,
superior to those of England or the rest of Europe. On this point
and for the smelting of iron we refer our readers to " OVERMAN on
the MANUFACTURE OF IRON," and will here introduce one of the
many American improvements in refining. This is a method of
making wrought-iron directly from the ore, patented by ALEX-
ANDER DICKERSON, of Newark, N. J., 22d July, 1850. "We have
seen some of the iron produced — it is apparently of the best quality.
Of this furnace, Fig. 21 represents a side view when complete.
Fig. 22, a longitudinal section of the same. Fig. 23, top view of
Fig. 23. Fig. 21.
cylinders, partly open. Figs. 24, and 25, large and small water plates
occupying places F and E respectively, through which small jets
of water continually flow, to prevent the flame from b'jmmg th^
76
THE PRACTICAL METAL- WORKER'S ASSISTANT.
cylinders. L and M, two upright cylinders, standing on the water
plates ; and between which cylinders in space B are placed in equal
Fig. 25
Fig. 22.
alternate layers, the pulverized ore and charcoal, or 25 per cent, in
weight of anthracite if that is substituted for charcoal.
The escape heat passes through an opening P in the afch freely
through space C between the masonry work D and the outer cylin-
der L, and also within the inner cylinder M through space A,
whereby the ore mixed with the coal is completely and uniformly
surrounded by the flame of heat and deoxidized, and yet perfectly
protected from the air, flame and noxious gases. When thus deox-
idized, one charge of the ore, by elevating valve K, is readily pre-
cipitated on the preparatory bottom Gr ; where it is stirred and freed
from the small particles of coal that accompany it from the cylin-
ders. It is then passed over on the puddling bottom G, where it
is further stirred and made up into balls, when it is ready for the
hammer or rolls.
In the fire chamber 0, the heat and flame may be produced from
wood, anthracite or bituminous coal.
The whole furnace much resembles an elongated ordinary pud-
dling furnace, with the addition of a preparatory bottom, over which
are placed the cylinders and their appendages.
While in operation, the cylinders are charged from the top with
the ore and coal pulverized and mixed. The cylinders are kept at
a red heat. The ore is thoroughly deoxidized in them, and de-
posited from them in successive charges on the preparatory and
puddling bottoms, as rapidly as the balls are taken from the latter
for the hammer or rolls. Thus the operation is continuous and
economical, as only the escape heat of the furnace is employed in
the cylinders.
REFINING AND WORKING OF IKON. 77
The whole is easily managed and worked, the operation is steady,
and the product certain and uniform. The iron produced is
represented to be extremely pliable, ductile, and malleable, and
applicable to all the arts. It is produced at a saving of about
40 per cent, of any other process. A ton and a half of anthra-
cite coal, and two and half to three tons of ore make a ton of
blooms in twelve hours. A furnace complete costs from $1,200 to
$1,500.
MANUFACTURE OF MALLEABLE IRON. — Formerly, wrought-iron
was obtained either directly from the ore, or from cast-iron, by a
process still in extensive operation, in which wood charcoal is re-
quired.
PUDDLING. — The crude cast-iron is remelted in quantities of
from half a ton to one ton, in a furnace called the chafery, or re-
finery, blown with blast ; it is kept fluid for about half an hour, and
then cast into a plate about four inches thick, which is purer, finer
in the grain than pig metal, and also much harder and whiter ; it
is then called refined metal. The plate when cold is broken up, and
from two to four hundred weight of the fragments, with a certain
proportion of lime, are piled on the hearth of the puddling furnace,
which is a reverberatory furnace without blast.
In about half an hour the iron begins to melt, and whilst it is in
the semi-fluid state, the workman stirs and turns it about with iron
tools ; he also throws small ladles full of water upon it from time
to time. In this condition the metal appears to ferment, and heaves
about from some internal change ; this is considered to arise from
the escape of the carbon in a volatilized form, which ignites at the
surface with spirits of blue flame : in about twenty minutes the
pasty condition gives way, and the iron takes a granulated form
without any apparent disposition to cohesion ; the fire is now urged
to the utmost, and before the metal becomes a stiff conglomerated
mass, the workman divides it into lumps or balls of about fifty
pounds in weight.
These balls are taken out one at a time, and shingled, or worked
under a massive helve or forge-hammer, that weighs six or eight
tons, and is moved by the steam-engine : this compresses the ball,
squeezes out the loose fluid matter, and converts it into a bloom, or
short rudely-formed bar. The bloom is then raised to the welding
heat in a reheating furnace, and again passed under the hammer, or
through grooved rollers, or it is submitted to both processes, by
which it is elongated into a rough bar. The shingling is sometimes
performed by large squeezers, somewhat like huge pliers, or by
roughened rollers that also serve to compress the iron ; but the
ponderous flat-faced helve is considered the more effectively to
expel the dross and foreign matters from the bloom, and to weld
the same more perfectly at every point of its length.
The machine for compressing and rolling puddler's balls, in-
vented by John I1. Winslow of Troy, New York, is very effective
and possesses many advantages, of which may be mentioned : 1.
78 THE PRACTICAL METALWORKER'S ASSISTANT.
Great expedition in shingling puddler's iron, one of these machines
being sufficient to do the work of twenty-five puddling furnaces.
2. The saving of shinglers' wages ; no wfete of iron ; turning out
the blooms while very hot, enabling the roller to reduce them to
very sound bars. 3. The ends of the blooms are thoroughly up-
set, a very small amount of power operates the machine, and little
or no expense for repairs.
The nature of the first part of this invention consists in rolling
and compressing puddler's balls or loops of iron into blooms, etc.,
by means of a rotating cam-formed compresser, combined with twc
or more rollers placed near to one another, and at the same distance
from the axis of motion of the compresser, so that the compression
and elongation of the loops will be due entirely to the eccentricity
of the compresser, the whole being so geared that the rollers shall
turn in the direction opposite to the motion of the compresser, that
the loop may be rotated and retained between the rollers and the
compresser : the surfaces of the rollers are formed with slight pro-
jections to take hold of and turn the loop of iron, and the surface
of the cam-formed compresser with teeth, which are very large at
first, or on that part of the compresser which first acts on the loop,
to squeeze out the impurities, and at the same time insure the
turning of the loop, and then gradually diminished until the surface
becomes quite or nearly smooth to finish the bloom.
And the second part of this invention consists in combining
with the compresser and rollers two cheeks, one on each side, and
provided with springs that force them towards one another that
they may yield to the ends of the loop of iron as it is lengthened
out by the action of the compresser and rollers, and at the same
time to make sufficient resistance to give a proper form to the ends
of the blooms, etc.
And the third part of this invention consists in combining with
the compresser and rollers a feeder or sliding frame, operated by
a projection on the compresser or the shaft thereof, to carry in the
ball of iron between the compresser and roller, as that part of the
compresser which is recessed for that purpose comes round to the
proper place for the introduction of the ball, and the discharge of
the bloom ; and also in combining in like manner a follower for
discharging the bloom after it has been completed.
(a) represents the frame of the machine properly adapted to the
intended purpose, but which may be varied at pleasure. In ap-
propriate boxes (bb) between the standards of this frame run the
journals of an eccentric roller (c), the periphery of which is cam-
formed and provided with cogs, for the purpose of squeezing the
ball of iron and forcing out the impurities, and gradually reducing
its diameter and elongating it. Below this squeezing roller are
arranged two fluted rollers (dd) whose journals are fitted to ap-
propriate boxes in the frame. These rollers constitute the concave
on which the ball of iron rests during the operations of the
squeezer ; cog wheels (ffg h) being employed to connect the shaft
REFIXIXG AXD WORKING OF IROX.
79
of the rollers with the shaft of the squeezer in such a manner
that the peripheries of the two rollers (dd) shall turn in the same
direction, and that of tbe squeezer in a reverse direction, and thus
cause the .ball or mass of iron during the operation of squeezing
Fig. 26.
to rotate about its axis, or nearly so, — the requisite power for this
purpose being communicated to the machine from some first mover
in any efficient manner. One of the bottom rollers (d) has a strong
flanch (i) on one side which projects sufficiently to pass within the
periphery of that part of the squeezer which acts on the iron,
80 THE PRACTICAL METAL-WORKER'S ASSISTANT
after it lias been so much elongated as to have one of its ends ap-
proach the flanch, and therefore towards the end of the operation
of the squeezer that end of the bloom ®r mass of iron which is
towards this flanch will be upset by it and properly formed. On
the side of the machine opposite to the flanch (i) is a hammer (j)
on the end of the bar (k) which slides in collars (I). The face of
this hammer is smooth, and made as hammers for working iron
usually are, and its edges are adapted to the peripheries of the two
rollers (dd) and to that part of the periphery of the squeezer which
acts on the bloom at the time the hammer is to strike the ends of
the bloom. A strong helical spring surrounds the bar (k) of the
hammer, .one end bearing against one of the collars (I), and the
other against the back of the hammer, so that its tension will
always force the hammer towards the flanch (i) of the roller (d) ;
and towards the outer end, the said bar (k) is provided with a spur
(m), the inner face of which is slightly rounded to bear against the
face of a cam (n), so formed that at each revolution of the bottom
rollers it gives the hammer two blows upon the bloom, and at
every revolution of the rollers the spring is liberated and the ham-
mer strikes the bloom, and thus upsets the ends, the flanch (i) in
this part of the operation performing the office of an anvil ; the
face of the cam is then made in the form of an inclined plane to
draw back the hammer preparatory to another operation.
Instead of forcing the hammer towards the bloom by a spring
and drawing it back by a cam, this arrangement may be reversed
by making the spring simply of sufficient length to draw back the
hammer, and reversing the cam that it may force the hammer to-
wards the bloom at the required time. And if desired, a lever,
operated in any desired manner, such as by a cam or crank, may
be used to operate the hammer instead of a cam, and under this
latter modification the spring may be dispensed with altogether by
connecting the hammer bar with the lever.
The bars are next cut into short pieces, and piled in groups of
four to six ; they are again raised to the welding heat in a reheat-
ing furnace, and passed through other rollers to weld them through-
out their length, and reduce them to the required sizes ; and some-
times the processes of cutting and welding are again repeated in
the manufacture of still superior kinds of iron.
A similar process of manufacture is still carried on, partly with
wood charcoal, in place of coals and coke ; the iron thus manufac-
tured, called charcoal iron, is much purer, but it is also more ex-
pensive in England ; it is sometimes, by way of distinction, left in
ridges from the hammer, when it is called dented iron.
The rollers or rolls of the iron works are turned of a variety of
forms, according to the section of the iron that is to be produced ;
in general one pair is used exclusively for each form of iron re-
quired; although in the imaginary sketch, Fig. 27, it is supposed that
the shaded portion represents the upper edge of the bottom roll ;
»ind that the top roll, which is not drawn, almost exactly meets the
REFINING AND WORKING OF IRON.
81
bottom one, with the exception of the grooves, and which are in
general turned partly in each roll, in the mariner denoted by the
black figures.
Fig. 27.
a 6 c defy h i
One pair will have a series of angular grooves for square iron,
gradually less and less, as a, b, c, Fig. 27, so that the bar may be
rapidly reduced without the necessity for altering the adjustment
of the rolls, which would lose much valuable time ; the flat bars are
prepared square, and then flattened in grooves, such as that at d\
round, or bolt iron, requires semicircular grooves, e ; but round iron
often shows a seam down one side, from the thin waste spread out
between the rolls being afterwards laid down without being welded,
when the iron is turned one quarter round and sent again through
the rollers : therefore the best round works are mostly forged from
square bars.
Figs. /and g are described as angle, and T iron; these are par-
ticularly used in making boilers, the ribs of iron steam- vessels ; also
frames, sashes, and various works requiring strength with lightness.
Plain cylindrical rollers serve for producing plate and sheet iron,
which vary in thickness from one inch to that of writing-paper, and
rolls turned like Fig. i, are employed for curvilinear ribbed plates,
or the corrugated iron, an elegant application lately patented for
roofs. Other rollers composed of two series of steeled discs, placed
upon spindles, are used to slit thin plates of iron about six inches
wide, into a number of small rods for the manufacture of nails, and
similar rods are also made of larger sizes called slit iron, they
always exhibit two ragged edges, and from being tied up in small
parcels, are also known as bundle iron.
Figs. 28, 29, 30 and 31, represent four amongst numerous other
sections of railway iron ; these bars are produced in rollers turned
with counterpart grooves ; as before, the shaded portions represent
fragments of the lower rollers, and the upper rollers are supposed
to occupy the spaces immediately adjoining the section of the rails.
For these also, three, four, or more grooves, varying gradually from
that of the roughly prepared bar, to that of the finished rail, are
employed, and this in like manner saves the necessity for adjusting
the distance between the rollers during the progress of the work.
6
82 THE PRACTICAL METALWORKER'S ASSISTANT.
All the foregoing rolls are supposed to be concentric, and to pro-
duce parallel bars and plates of the respective sections; but in
making fish-bellied railway bars (no longer used), taper plates for
coach springs, and similar tapered works, the rollers, whether plain
or grooved, are turned eccentrically, so as to make the works re
spectively thicker or deeper in the middle, as in Fig. 32 ; this re-
quires additional dexterity on the part of the workman to introduce
the material at the proper time of the revolution, upon which it is
unnecessary to enlarge.
The general effect of the manufacture of malleable iron is to de-
prive the cast-iron of its carbon ; this is done in the puddling fur-
nace ; the original crystalline structure gives way to the fibrous,
from the working under the hammer and rollers, by which every
individual particle or crystal is drawn- out as it were into a thread,
the multitude of which constitute the fibrous bar or metallic rope,
to which it has some resemblance except in the absence of twist.
The rod may now be bent in any direction without risk of fracture ;
and the superior kinds, even when cold, may be absolutely tied in
a knot, like a rope, when a sufficient force is applied.
Should it however occur that the first operation, or shingling
process, were imperfectly performed, the error will be extended in
a proportional degree throughout the mass, which will account for
the general continuance of any imperfection throughout the bar of
iron, or a considerable length of the wire in which the reduc-
tion or elongation is further extended ; and to which evil all
metals and alloys subjected to these processes of elongation are also
liable.
Malleable iron is divided into three principal varieties. First,
red-short iron; secondly, cold-short iron; thirdly, iron partaking
of neither of these evils, and which may be so far denominated
pure malleable iron.
The first kind is brittle when hot, but extremely soft and ductile
whilst cold. This is considered to result from the presence of a
little carbon. The cold-short withstands the greatesl degree of heat
without fusion, and may be forged under the heaviest hammers
when hot, but it is brittle when cold. This is attributed to the
presence of a little silex. The third kind is considered to be en-
tirely free from either carbon or silex, etc., and to be the pure sim-
ple metal ; but in the general way the characters of iron are
intermediate between those described.
From one and a half to two tons of pig-iron have been used to
produce one ton of malleable iron ; bat the average quantity is now
from twenty-six to twenty-seven tons for each twenty tons of produce.
The forge pig, ballast, and white cast-iron, is the kind principally
used, as it contains least carbon, the whole of which should be ex-
expelled in the conversion of the cast metal into wrought-iron.
It appears to be unnecessary to attempt any minute description
of the different marks and qualities of iron. First, as these de-
scriptions have been minutely given in many works ; and secondly,
MANUFACTURE OF STEEL. 83
as in common with most other articles, the quality of iron governs
the price.
I will only add, that little can be known of the character of iron
from its outside appearance, beyond that of its having been well
or ill manufactured, so far as regards its formation into bars. The
smith is principally guided by the fracture when he breaks down
the iron, that is, when the bar is nicked on opposite sides with the
cold chisel, laid across the anvil upon a strip of iron near to the
cut that it may stand hollow, and the blows of the pane of the
sledge-hammer are directed upon the cut.
The judgment will be partly formed upon the force thus re-
quired in breaking the iron ; the weakest and worse kinds will
yield very readily, — when small, sometimes even to the blow of
the chisel alone, and will then show a coarse and brilliant appear-
ance, entirely granular or crystalline. This iron would be called
very common and bad. If, on the other hand, the iron breaks
with difficulty, and the liife of separation, instead of being moder-
ately flat, is irregular, or presents what may be called a hilly sur-
face, the sides of which have a fibrous structure and a sort of lead-
colored or a dull-gray hue, this kind will have a large proportion
of fibre, and it will be called excellent tough iron. Other kinds
will be intermediate, and present partly the crystalline and partly
the fibrous appearance, and their relative values will depend upon
how nearly they approach the one or other character.
Another trial is the extent to which iron, when slightly nicked,
may be bent to and fro without breaking. The coarse brittle kind
will scarcely bend even once, whereas superior kinds, especially
stub, charcoal, and dented irons, will often endure many deflections
before fracture, and when nicked on the outside only and doubled
flat together, will bend as an arch and partly split open through
the centre of the bar, somewhere near the bottom of the cut .made
with the chisel, the entire fracture presenting the beautiful fibrous
appearance and dull leaden hue before described.
CHAPTER V.
MANUFACTURE OF STEEL.
STEEL is manufactured from pure maiieao e iron by the process
called cementation. The Swedish iron from the Dannemora mines,
marked with the letter L in the centre of a circle, and called
" Hoop L," is generally preferred. Irons of a few other marks are
also used for second-rate kinds of steel. The bars are arranged in a
furnace that consists of two troughs, about fourteen feet long and
two feet square. A layer of charcoal-powder is spread over the
bottom, then a layer of bars, and so on alternately. The full
84 THE PRACTICAL METAL-WORKER'S ASSISTANT.
charge is about ten tons. The top is covered over first with char-
coal, then sand, and lastly with the waste or slush from the grind-
stone trough, applied wet, so as to cement the whole closely down,
for the entire exclusion of the air.
A coal fire is now lighted below and between the troughs ; and
at the end of about seven days the bars are found to have in-
creased in weight the one hundred and fiftieth part, by an absorp-
tion of carbon, and to present, when broken, a fracture more crys-
talline, although less shining, than before. The bars, when thus
converted, are also covered with blisters, apparently from the ex-
pansion of the minute bubbles of air within them ; this gives rise
to the appellation, blistered steel.
The continuance of the process of cementation introduces more
and more carbon, and renders the bars more fusible, and would
ultimately cause them to ran into a mass if the heat were not
checked. To avoid this mischief a bar is occasionally withdrawn
and broken to watch the progress ; and the work is complete when,
the cementation has extended to the centre of the bars. The con-
version occupies, with the time for charging and emptying the
furnace, about fourteen days.
A very small quantity of steel- is employed in the blistered state,
for welding to iron for certain parts of mechanism, but not for
edge-tools. The bulk of the blistered steel is passed through one
of the two following processes, by which it is made either into
shear-steel or cast-steel.
Shear- steel is produced by piling together six or eight pieces of
blistered-steel, about thirty inches long, and securing the ends
within an iron ring, terminating in a bar about five feet long by
way of a handle. They are .then brought to a welding heat in a
furnace, and submitted to the helve or tilt hammer, which unites
and extends them into a bar called shear-steel, from its having been
much used in the manufacture of shears for cloth mills, and also
German steel, from having been in former years procured from
that country. Sometimes the bars are again cut and welded, and
called double-shear steel, from the repetition.
This process of working, as in the manufacture of iron, restores
the fibrous character, and retains the property of welding : the shear
steel is close, hard, and elastic ; it is much used for tools, composed
jointly of steel and iron ; its superior elasticity also adapts it to the
formation of springs, and some kinds are prepared expressly for. the
same under the name of spring-steel.
In making cast-steel, about twenty-six or twenty-eight pounds of
fragments of blistered-steel, selected from different varieties, are
placed in a crucible made of clay, shaped like a barrel, and fitted
with a cover, which is cemented down with a fusible lute that melts
after a time the better to secure the joining. Either one or two
pots are exposed to a vivid heat, in a furnace like the brass-founders'
air-furnace, in which the blistered-steel is thoroughly melted in the
course of three or four hours ; it is then removed by the workman
MANUFACTURE OF STEEL. 85
in a glowing state, and poured into a mould of iron, either two
inches square for bars, or about six by eighteen inches, for rolling
into sheet-steel. For large ingots the contents of two or more pots
are run together in the same mould, but it requires extremely great
care in managing the very intense temperature, that it shall be alike
in both or all the pots.
The ingots are reheated in an open fire much like that of the
common forge, and are passed under a heavy hammer weighing
several tons,. such as those of iron- works; the blows are given
gently at first, owing to the crystalline nature of the mass, but as
the fibre is eliminated the strength of the blows is increased.
Steel is reduced under the heavy hammer to sizes as small as
three-quarters of an inch square. Smaller bars are finished under
tilt hammers, which are much lighter than the preceding, move
considerably quicker, and are actuated by springs instead of grav-
ity alone ; these condense the steel to the utmost. Boilers are also
used, especially for steel of round, half-round, and triangular sec-
tions, but the tilt hammer is greatly preferred.
Cast-steel is the most uniform in quality, the hardest, and alto-
gether the best adapted to the formation of cutting tools, especially
those made entirely of steel ; but much of the cast-steel will not
endure the ordinary process of welding, but will fly in pieces under
the hammer when struck.
In respect, to steel, the same general remarks offered upon iron
may be repeated, namely, that price in a great measure governs
quality. Steel when broken does not show the fibrous character
of iron, and in general the harder or harsher the steel, the more
irregular or the less nearly flat will be its fracture.
The blistered-steel should appear throughout its substance of an
uniform appearance, namely, crystalline and coarse, much like infe-
rior iron, but with less lustre and less of the bluish tint; when but
partially converted, the Him of iron will be readily distinguished
in the centre. The blistered-steel when it has been once passed
through the fire and well Iwmmered, assumes as may be supposed a
much finer grain, as in fact the operation converts it (although in
the small way) into shear-steeL
Shear-steel breaks with a much finer fracture, but the crystalline
appearance is still readily distinguished. Cast-steel is in genera] the
finest of all in its fracture, and unless closely inspected, its separate
crystals or granulations should be scarcely observable, but the ap-
pearance should be that of a fine, light slaty-gray tint, almost with-
out lustre.
The quality of steel is considerably improved, especially as re-
ganls cutting tools, when after being forged it is hammer-hardened,
or well worked with the hammer until quite cold, as this tends to
close the " pores" and to make the material more dense ; above all
things excess of heat should be avoided, as it makes the grain
coarse and shining, almost like that of bad iron, and which deteri-
oration can be only partially restored, by good sound hammering
under a peculiar management The particular degrees of heat at
86 THE PRACTICAL METAL-WORKER'S ASSISTANT.
which different samples of iron and steel, bearing the same name,
should be worked, can only be found by trial ; and it would be
hardly possible to describe the shades of difference.
It would have been incompatible with the nature of this work to
have entered more largely into the manufacture of iron and steel,
or to have attempted the notice of all the various alloys of steel
which have received many attractive denominations, especially
when so much has been already written on the subject.
Of all the works published on the manufacture of iron and steel,
those of the most importance are "Overman on Iron," Lesley's
"Iron Manufacturers' Guide," Truran's "Manufacture of Iron,"
'• Reports of Experiments on Metals for Cannon," by Officers U. S.
Army, Captain Rodman's Reports on the same subject, " Karsten
on Iron," and Dr. Hartmann's '' Iron Manufacturers' Hand Book,"*
the two latter in German, and the collection of Mushet's papers,
which have appeared in the "Philosophical Magazine" at various
times subsequent to 1798, and were collected and published by
himself under the title " Papers on Iron and Steel."
Of the more brief and popular accounts of this subject, the best
are Aikin's Dictionary of Chemistry and Mineralogy ; three vol-
umes on the Manufactures in Metal, in Lardner's Cyclopedia ; and
lire's Dictionary of Manufactures and Mines, which contain a very
large store of information on the metals generally. The reader will
also consult with advantage Aikin's ''Illustrations of Arts and Man-
ufactures," and an admirable article in Appleton's " New American
Cyclopedia."
CHAPTER VI
FORGING IRON AND STEEL.
IN entering upon this subject, which performs so important and
indispensable a part in every branch of mechanical industry, it is
proposed first to notice some of the general methods pursued, com-
mencing with the heaviest works, and gradually proceeding to
those of the smallest proportions. This arrangement however shall
not prevent us for greater convenience, giving in a chapter subse-
quent to this general view, a very thorough one on Wrought-Iron
in large Masses, alone.
After this, the management of the fire, and the degrees of heat
required for various purposes, will be described ; and then the ele-
mentary practice of forging will be attempted : those works made
principally in one piece will be first treated of, and afterwards such
as are composed of two or more parts, and which require the opera-
tion o*" welding.
* A. translation of this important work will shortly appear, from the In-
dustrial Press of lleury Carey Buird, Philadelphia, ,
FORGING IROX AND STEEL. 87
The heaviest works of all, are generally heated in air furnaces
of various descriptions, some of which resemble but greatly exceed
in size those employed in the works where iron is manufactured,
and in which the process of forging may be truly considered to
commence with the very first blow given upon the bo.ll, as it leaves
the puddling furnace for being converted into a bloom.
At these works, in addition to the ordinary manufacture of bar,
plate, and hoop iron in all their varieties, the hammer-men are em-
ployed in preparing masses, technically called "uses" which mean
pieces to be used in the construction of certain large works, by the
combination or welding of several of these masses. A square shaft,
to be used at an iron- works, was made by laying together sixteen
square pieces, measuring collectively about twenty-six inches square,
and six feet long. These were bound together, and put into a power-
ful air furnace, and the ends of the group were welded into a solid
mass under the heavy hammer weighing five tons ; the weld was
afterwards extended throughout the length. The paddle-shafts of
the largest steam-ships are wrought by successive additions at the
one end, as follows : A slab or use is welded on one side close to
the end, and when drawn down to the common thickness, the
additional matter becomes thrown into the length ; the next use
is then placed on the adjoining side of the as yet square shaft,
and also drawn into the length, and so on until the full measure is
attained.
These ponderous masses are managed with far more facility than
might be expected by those who have never witnessed such inter-
esting proceedings. First, the " heat " has a long iron rod attached
to it in continuation of its axis, to serve as a "porter" or guide rod ;
the mass is suspended under a traversing crane at that point where
it is nearly equipoised : the crane not only serves to swing it round
from the fire to the hammer, but the traverse motion also moves
the work endways upon the anvil, and small changes of elevation
ar* sometimes affected by a screw adjustment in the suspending
chain. The circular form is obtained by shifting the work round
upon its axis by means of a cross lever fixed upon the porter, and
moved by one or two men, so as to expose each part of the circum-
ference to the action of the helve ; this is readily done, as the crane
terminates in a pulley, around which an endless band of chain is
placed, and the work lies within the chain, which shifts 'round
when the work is turned upon the anvil : the precision of the forg-
ings produced by these means is very surprising. (See p. 110).
A similar mode of work is adopted on a smaller scale for many
of the spindles, shafts, and other parts of ordinary mechanism, which
are forged under the great hammer, often of several bars piled to
gether and fagoted; a suitable term, as they are frequently made of
a round bar in the centre, and a group of bars of angular section,
called mitre iron, around the same, which are temporarily wedged
within a hoop, somewhat after the manner of a fagot of wood. Such
works are likewise made of scrau-iron, which consists of a strange
88 THE PRACTICAL METAL -WORKER'S ASSISTANT.
heterogeneous medley of odd scraps and refuse from a thousand
works, scarcely two pieces of which are alike.
A number of these fragments are enveloped in an old piece of
sheet iron, and held together by a hoop, the mass is raised to the
welding heat in a blast or air furnace, and the whole is consolidated
and drawn down under the tilt-hammer ; one long bar that serves
as the porter being welded on by the first blow. The mingling of
the fibres in the scrap-iron is considered highly favorable to the
strength of the bar produced. The scrap-iron is sometimes twisted
during the process of manufacture, to lay all the filaments like a
rope, and prevent the formation of spills, or the longitudinal dirty
seams found on the surface of inferior iron.
Sometimes the formation of the scrap-iron is immediately followed
by the production of the shafts and other heavy works for which it
is required ; at other times the masses are elongated into bars sold
tinder the name of scrap-iron, although it is very questionable if
all the iron that is so named is produced in the manner implied.
The long furnaces are particularly well suited to straight works
and bars, but when the objects get shorter and of more complex
figures, the open fire or ordinary smith's hearth is employed. This,
when of the largest kind, is a trough or pit of brickwork about six
feet square, elevated only about six inches from the ground ; the
one side of the hearth is extended into a vertical wall leading to
the chimne}r, the lower end of which terminates in a hood usually
of stout plate iron, which serves to collect the smoke from the fire.
The back wall of the forge is fitted with a large cast-iron plate, or
a back, in the centre of which is a very thick projecting nozzle also
of iron, perforated for admitting the wind used to urge the fire ; the
aperture is called the tuyere.
The blast is sometimes supplied from ordinary bellows of various
forms ; at other times, by three enormous air-pumps, which lead into
a fourth cylinder or regulator, the piston of which is loaded with
weights, so as to force the air through pipes all over the smithy, a^id
every fire has a valve to regulate its individual blast ; but the more
modern and general plan is the revolving fan, also worked by the
engine, the blast from which is similarly distributed.
In some cases the cast-iron forge back is made hollow, that a
stream of water may circulate through it from a small cistern ; the
water-back is thereby prevented from becoming so hot as the others,
and its durability is much increased. In other cases the air, in its
passage from the blowing apparatus, flows through chambers in
the back plate so as to become heated in its progress, and thus to
urge the fire with hot blast, which is by many considered to eft'ect a
very great economy in the fuel.
Some heavy works of rather complex form, such as anchors, are
most conveniently managed by hand forging; many of these require
two gangs of men with heavy sledge-hammers, each consisting of
six to twelve men, who relieve each other at short intervals, as the
work is exceedingly laborious. Their hammers are swung round
FORGING IROX AXD STEEL. 89
and made to fall upon one particular spot with great uniformity ;
the conductor of this noisy, although dumb concert so far as relates
to voice, stands at a respectful distance, and directs the blows of his
assistants with a long wooden wand. The Hercules, or crane, used
for transferring the work from the fire to the anvil, which is at
about the same elevation as the fire itself, is still retained.
The square shanks of anchors are partly forged under a vertical
hammer of very simple construction, called a " monkey." It con-
sists of a long iron bar running very loosely through an eye or
aperture several feet above the anvil, and terminating at foot in a
mass of iron, or the ram. The hammer is elevated by means of a
chain, attached to the rod and also to a drum overhead, which is
put into gear with the engine, and suddenly released by a simple
contrivance, when the hammer has reached the height of from two
to five feet, according to circumstances. The ram is made to fall
upon any precise spot indicated by the wand of the foreman, as it
has a horizontal range of some twenty inches from the central posi-
tion, and is guided by two slight guy rods, hooked to the ram and
placed at right angles ; the guys are held by two men, who watch
the directions given. This contrivance is far more effective than
the blows of the sledge-hammers, and although now but little used
is perhaps more suitable to such purposes than the helve or lift-
hammer, which always ascends to one height, and falls upon one
fixed spot.
The square shank of the anchor, and works of the same section,
are readily shifted the exact quarter circle, as the sling-chain is
made with flat links, each a trifle longer than the side of the square
of the work, which, therefore, bears quite flat upon one link, and,
when twisted, it shifts the chain the space of a link, and rests as
before.
Many implements and tools, such as shovels, spades, mattocks,
and cleavers, are partly forged under the tilt-hammer ; the prepara-
tory processes, called moulding, which include the insertion of the
steel, are done by ordinary hand forging. The objects are then
spread out under the broad face of the tilt-hammer, the workman
in such cases being sometimes seated on a chair suspended from
the ceiling, and, by paddling about with his feet, he places himself
with great dexterity in front or on either side of the anvil wjth the
progressive changes of the work: the concluding processes are
mostly done by hand with the usual tools. A similar arrangement
is also adopted in tilting small-sized steel.
With the reduction of size in the objects to be forged, the num-
ber of hands is also lessened, and the crane required for heavy work
is abandoned for a chain or sling from the ceiling ; but, for the
majority of purposes, two men only are required, when the work
is said to be two-handed. The principal, or the fireman, takes the
management of the work both in the fire and upon the anvil ; he
directs and assists with a small hammer of fromVvvo to four pounds
weight ; the duty of his assistant is to blow the bellows and wield
20 THE PRACTICAL METAL-WORKERS ASSISTANT.
the sledge-hammer, that weighs from about ten to fourteen pounds,
although sometimes more, and from which he derives his name of
hammer-man.
As the works to be forged become smaller, the hearth is gradually
lessened in size, and more elevated, so as to stand about two and a
half feet from the ground ; it is now built hollow, with an arch
beneath serving as the ash-pit to receive the cinders and clinkers.
The single hearths are made about a yard square, and those forges
which have two fires under the same hood, measure about two
yards by one ; a double trough, to contain water in the one com-
partment and coals in the other, is usually added, and the ordinary
double bellows is used. In proportion as the hearth is more
elevated, so is the anvil likewise, that in ordinary use standing
about two feet or two and a half feet from the ground, its weight
being from two to four hundred-weight.
Numerous small works are forged at once from the end of the
bar of iron, which then also serves the office of the porter required
for heavy masses ; but when the small objects are cut off from the
bar, or the pieces are too short to be held in the hand, tongs of
different forms are needful to grasp the work. These are made of
various shapes, magnitudes, and lengths according to circumstances ;
but the annexed figures will serve to explain some of the most
general kinds, although variations are continually made in their
form to meet peculiar cases.
Figs. 33 and 34 are called flat-lit tongs ; these are either made to
fit very close, as in Fig. 34, for thin works, or to stand more open
Figs. 34.
35.
36
Fig. 33.
as in Fig. 33, for thicker bars, but always parallel ; and a ring, or
coupler, is put upon the handles, or reins, to maintain the grip upon
the work ; others of the same general form are made with hollow,
half-round bits ; but it is much better they should be angular, like
the ends of Fig. 35, as then they serve equally ,w ell for round bars,
FORGING IRON AND STEEL. 91
or for square bars held upon their opposite angles. Tongs that are
made long, and swelled open behind, as in Fig. 35, are very excel-
lent for general purposes, and also serve for bolts and similar objects
with the heads placed inwards. The pincer tongs, Fig. 36, are also
applied to similar uses, and serve for shorter bolts.
Fig. 37 represents tongs much used at Sheffield, amongst the
cutlers; they are called crook-bit tongs; their jaws overhang the side
so as to allow the bar of iron or steel to pass down beside the
rivet, and the nib at the end prevents the rod from being displaced
by the jar of hammering ; these are very convenient. Fig. 38, or
the hammer tongs, are used for managing works punched with
holes, such as hammers and hatchets: as the pins enter the holes,
and maintain the grasp, they should be made stout and long, so as
to admit of being repaired from time to time, as the bits get de-
stroyed by the fire.
Fig. 39, or hoop tongs, are very much used by ship-smiths, for
grasping hoops and rings, which may be then worked either on
the edge, when laid flat on the anvil, or on the side when upon
the beak-iron: and lastly, Fig. 40 represents the smith's pliers, or
light tongs, used for picking up little pieces of iron, or small tools
and punches, many of which are continually driven out upon the
ground in the ordinary course of work ; they are also convenient
in hardening small tools.
In addition to the hearth, anvil, and tongs, the smithy contains
a number of chisels, punches, and swages or striking tools, called
also top and bottom tools, of a variety of suitable forms and gen-
erally in pairs ; these may be considered as reduced copies of the
grooves turned in the rollers, and occasionally made on the faces
of the tilt-hammers of the iron- works for the production of square,
flat, round, T form iron, angle iron, and railway bars, as referred
to. The bottom tools of the ordinary smith's shop, have square
tangs to fit the large hole in the anvil ; in using them the fireman
holds the work upon the bottom tool, and above the work he
places the top or rod tool, which is then struck by the sledge-ham-
mer of his assistant.
In fitting the hazel rods to the top tools the rods are alternately
wetted in the middle of their length, and warmed over the fire to
soften them, that portion is then twisted like a rope, and the rod is
wound once round the head of the tool and retained by an iron
ferrule or coupler ; a rigid iron handle would jar the hand.
When these tools are used for large works, a square plate of
sheet-iron, with a whole punched in the middle of it, is put on the
rod towards the tool, to shield the hand of the workman from the
heat ; and it not unfrequently happens with such large works thai
the rod catches fire, and the tool is then dipped at short intervals
in the slake trough to extinguish it.
The smith who works without any helpmate is much more circum-
scribed as to tools, and he is from necessity compelled to abandon
all those used in pairs, unless the upper tools have some mechani-
92
THE PRACTICAL METAL-WORKERS ASSISTANT.
cal guide to support and direct them. In addition to the anvil ho
only uses the fixed cutter and heading tools ; he may occasionally
support the end of the tongs in a hook attached to his apron-
string, or suspended from his neck, whilst he applies a hand-chisel,
a punch, or a name-mark in the left hand, and strikes with the
hammer held in the right. The method is however ample for a
variety of small works, such as cutlery, tools, nails, and small iron-
mongery, which are wrought almost exclusively by the hand-
hammer.
Attempts to work small tilt-hammers with the foot have been
found generally ineffective, as the attention of the individual is
too much subdivided in managing the whole, neither is his
strength sufficient for a continued exertion at such work ; but the
" Oliver" which we shall now describe, is one of the best tools of
this class.
THE OLIVER, OR SMALL LIFT-HAMMER.— Fig. 41 represents a
species of lift-hammer worked by the foot. The hammer head is
Fig. 41.
about two and a half inches square and ten long, with a swage
tool having a conical crease attached to it, and a corresponding
swage is fixed in a square cast-iron anvil block, about twelve
inches square, and six deep, with one or two round holes for
punching, etc. The hammer handle is about two to two and a half
1'eet long, and mounted in a cross spindle nearly as long, supported in
n, wooden frame between end screws, to adjust the groove in tho
hammer face to that in the anvil block. A short arm, five^or six
mches long, is attached to the righ't end of the hammer axis, and
FOKGING IKON AND STEEL.
98
from this arm proceeds a cord to a spring pole overhead, and also
a chain to a treadle a little above the floor of the smithy.
When left to itself the hammer handle is raised to nearly a ver-
tical position by the spring, and it is brought down very readily
with the foot, so as to give good hard blows at the commencement
of moulding the objects, and then light blows for finishing them.
The machine was used when the author first saw it, in making
long stout nails, intended for fixing the tires of wheels, secured
within the felloes by washers and riveting; the nails were made
very nicely round and taper, and were forged expeditiously.
For single hand-forging, the fire becomes still further reduced
in size, and proportionally elevated from the ground. A portable
forge of suitable dimensions for such work, and made entirely of
iron, is represented in Fig. 42. The bellows are placed beneath
the hearth and worked by a treadle.
Fig. 42.
This forge is also occasionally fitted with a furnace for melting
small quantities of metal, and with various apparatus for other
applications of heat, such as soldering, either with a small charcoal
fire, or a lamp and blowpipe, which are likewise urged with the
I
94 THE PRACTICAL METAL-WORKER^ ASSISTANT.
bellows. These applications, and also that of hardening and tem-
pering tools, which will be severally returned to at their respective
places, are much facilitated by the bellows being worked with the
foot, as it leaves both hands at liberty for the management either
of the work or fire, with the so-called fire-irons, which include a
poker, a slice or shovel, and a rake, in addition to the supply of
tongs of some of the former shown.
The forge represented is sufficiently powerful for a moderate
share of those works which require the use of the sledge-hammer ;
but, when the latter tool is used, the anvil should not fall short of
one hundred pounds in weight ; and the heavier it is, the less it
will rebound under the hammer.
MANAGEMENT OF THE FIRE : THE DEGREES OF HEAT. — The ordi-
nary fuel for the smith's forge is coal, and the kinds to be pre-
ferred are such as are dense and free from metallic matters, as
these are generally accompanied with sulphur, which is highly
detrimental.
Copper is usually forged in a coke fire — silver and gold in those
made of charcoal ; but the hearths do not materially differ from
those used for iron. Compressed peat charcoal has been strongly
recommended on account of its freedom from sulphur — one of the
greatest enemies in nearly all metallurgic operations.
The fire is sometimes made open, at other times hollow, or like
a tunnel ; and the larger the fire is required to be, so much the
more distant is it situated from the tuyere iron. Before lighting the
fire, the useful cinders are first turned back on the hearth, and the
exhausted dust or slack is cleared away from the iron back and
thrown into the ash-pit; a fair-sized heap of shavings is then
lighted, and allowed to burn until the flame is nearly extinguished,
when the embers are covered over with the cinders, and the bel-
lows are urged A dense white smoke first rises, and, in two or
three minutes, the flame bursts forth, unless the fire be choked,
when the poker is carefully passed into the mouth of the tuyere.
The work is now laid on the fire, and covered over with green or
fresh coals, which are beaten around the tuyere and the work, the
blast being continued all the while ; the whole mass will soon
be in a state of ignition. A heap of fresh coals is always kept at
the outside wall of the fire, and they are gradually advanced at
intervals into the centre of the flame to make up for those con-
sumed.
In making a large hollow fire, after a good-sized fire has been
lighted in the ordinary way, the ignited fuel is brought forward on
the hearth to expose the tuyere iron, into the central aperture of
which the poker is introduced. A mass of small wetted coal is beaten
hard round the poker to constitute the stock, the magnitude of
which will depend on the distance at which the fire is required to
stand off, and a second stock is also made opposite the first, the
two resembling two hills with the lighted fuel lying between them.
The durability of the fire will depend on the stocks being hard
FORGING IRON AND STEEL. 95
rammed, which, for large works, is often done with the sledge-
hammer. The work is now laid in the hollow just opposite the
blast-pipe, and covered on its two sides and top with thin pieces
of wood, and a heap of wetted coals is carefully banked up around
the same and beaten down with the slice or shovel. When care-
fully done, the heap is made to assume the smooth form of an em-
bankment of earthwork. The bellows are blown gently all the
time, and the work is not withdrawn until the wood is consumed,
and the flame peeps through at each end of the aperture, so as to
cake the coals well together into a hard mass; after which the work
may be removed or shifted about without any risk of breaking
down the fire.
In localities where wood is scarce, small iron rods are placed
around the principal mass, often designated the heat; the small
rods are first withdrawn when the fire has burned up, to allow
room for the removal of the work.
Sometimes when a fire is required only for hardening, the cen-
tering of the arch is made entirely of wood, either in one or several
pieces : and in this manner it may be built of any required form,
as angular for knees, circular for hoops, and so on (although such
works are usually done in open fires, which resemble the above in
all respects, except the covering-in or roof) : small coal is thrown
at intervals into the hollow fire to replace that which is burned,
and by careful management one of these combustible edifices will
last half a day, or even the entire day, without renewal. Occa-
sionally, the stock around the tuyere iron will serve with a little
repair for a second day, if, when the fire is turned back at night, that
part is allowed to remain, and the fire is extinguished with water.
When a small hollow fire is required, the same general methods
are less carefully followed, and an iron tube introduced amidst the
coals, makes a very convenient muffle or oven for some purposes.
In forging, the iron or steel is in almost every case heated to a
greater or less degree, to make it softer and more malleable by
lessening its cohesion ; the softening goes on increasing with the
accession of temperature, until it arrives at a point beyond that
which can be usefully employed, or at which the material, whether
iron or steel, falls in pieces under the blows of the hammer, but
which degree is very different with various materials, and even
with varieties bearing the same name.
Pure iron will bear an almost unlimited degree of heat. The hot
short iron bears much less, and is in fact very brittle when heated.
Other kinds are intermediate. Of steel, the shear-steel will gen-
erally bear the highest temperature, the blistered-steel the next,
and the cast-steel the least of all. But all these kinds, especially
cast-steel, differ very much according to the processes of manu-
facture, as some cast-steel may ba readily welded, but it is then
somewhat less certain to harden porfectly.
Without attempting any refine:! division, I may add, the smith
commonly speaks of five degrees of temperature, namely :
96 THE PRACTICAL METAL- WORKER'S ASSISTANT.
The black-red heat, just visible by daylight ;
The low-red heat ;
The bright-red heat, when the black scales may be seen ;
The white-heat, when the scales are scarcely visible ;
The welding-heat, when the iron begins to burn with vivid
sparks.
Steel requires on the whole very much more precaution as to
the degree of heat, than iron. The temperature of cast steel
should not generally exceed a bright-red heat ; that of blistered
and shear-steel that of a moderate white-heat. Although steel
cannot in consequence be so far softened in the fire as iron, and is
therefore always more dense and harder to forge ; still from its su-
perior cohesion it bears a much greater amount of bard work under
the hammer when it is not over-heated or burned ; but the small-
est available temperature should be always employed with this
material, as in fact with all others.
It has been recommended to try by experiment the lowest de-
gree of heat at which every sample of steel will harden, and in
forging always to keep a trifle below that point. This proposal
however is rarely tried, and still less followed, as the usual attempt
is to lessen the labor of forging by softening the steel so far as it
is safely practicable.
Iron is more commonly worked at the bright-red and the white-
heats, the welding-heat being reserved for those cases in which
welding is required ; or others in which, from the great extension
or working of the iron, there is risk of separating its fibres or
Iamina3, so as to cause the work to become unsound or hollow
from the disrupture of its substance ; whereas the same processes
being carried on at the welding temperature, the work would be
kept sound, as every bk>w would effect the operation of welding
rather than that of separation. The cracks and defects in iron are
generally very plainly shown by a difference in color at the parts
when they are heated to a dull-red. This method of trial is often
had recourse to in examining the soundness both of new and old
forgings.
When a piece of forged work is required to be particularly
sound, it is a common practice to subject every part of the ma-
terial in succession to a welding heat, and to work it well under
the hammer, as a repetition of the process of manufacture to in-
sure the perfection of the iron ; this is technically called taking
a heat over it — in fact, a heat is generally understood to imply the
welding heat. For a two-inch shaft of the soundest quality, two
and a half inch iron would be selected, to allow for the reduction
in the fire and the lathe. Some also twist the iron before the ham-
mering to prevent it from becoming " spilly"
The use of sand sprinkled upon the iron is to preserve it from
absolute contact with the air, which would cause it to waste away
from the oxidation of its surface, and fall off in scales around the
anvil. If the sand is thrown on when the metal is only at the full
ORDINARY PRACTICE OF FORGING. 97
red lieat it falls off without adhering; but, when the white lieat is ap-
proached, the sand begins to adhere to the iron ; it next melts on
its surface, over which it then runs like fluid glass, and defends it
from the air. When this point has been rather exceeded, so that
the metal nevertheless begins to burn with vivid sparks and a
hissing noise like fireworks, the welding temperature is arrived at,
and which should not be exceeded. The sparks are, however,
considered a sign of a -dirty fire or bad iron, as the purer the iron
the less it is subject to waste or oxidation, in the course of work.
In welding two pieces of iron together, care must be taken that
both arrive at the welding heat at the same moment ; it may be
necessary to keep one of the pieces a little on one side of the most
intense part of the fire (which is just opposite the blast), should
the one be in advance of the other. In all cases, a certain amount
of time is essential, otherwise, if the fire be unnecessarily urged,
the outer case of the iron may be at the point of ignition before
the centre has exceeded the red heat. In welding iron to steel,
the latter must be heated in a considerably less degree than the
iron, the welding heat of steel being lower from its greater fusi-
bility. But the process of welding will be separately considered
under a few of its most general applications, when the ordinary
practice of forging has been discussed, and to which we will now
proceed.
ORDINARY PRACTICE OF FORGING.
THE general practices of forging works from the bar of iron or
steel are, for the most part, included in the three following modes :
the first two occur in almost every case, and frequently all three
together, namely :
By drawing -down, or reduction;
"By jumping, or up-setting; otherwise, thickening and shortening;
By building-up, or welding.
When it is desired to reduce the general thickness of the object,
both in length and width, then the flat face of the hammer is made
to fall level upon the work; but, where the length or breadth
alone is to be extended, the pane or narrow edge of the hammer
is first used, and its blows are directed at the right angles to the
direction in which the iron is to be spread. To meet the variety
of cases which occur, the smith has hammers in which the panes
are made in different ways — either at right angles to the handle,
parallel with the same, or oblique.
In order to obtain the same results with more precision and
effect, tools of the same characters, but which are struck with the
7
98 THE PRACTICAL METAL-WORKER'S ASSISTANT.
sledge-hammer, are also commonly used. Those with flat faces
are made like hammers, and usually with similar handles, except
that, for the convenience of reversing them, they are not wedged
in ; these are called set-hammers ; others, which have very broad
faces, are called flatters ; and the top tools, with narrow round
edges like the pane of the hammer, are called top-fullers. They
all have the ordinary hazel rods.
When the sides of the object are required to be parallel, and it
is to be reduced both in width and thickness, the flat face of the
hammer is made to fall parallel with the anvil, as represented in
Fig. 43, or oblique, for producing taper pieces, as in Fig. 44, and.
action and reaction being equal, the lower face of the work re-
ceives the same absolute blow from the anvil as that applied
above by the hammer itself. It is not requisite, therefore, to pre-
sent every one of the four sides to the hammer, but any two at
right angles to each other. This is only true for works of moderate
dimensions ; in large masses, such as anchors, the soft doughy state
of the metal acts as a cushion, and greatly lessens the recoil of the
anvil, and on this account such works are presented to the ham-
mer on all four sides. It is also very injudicious in such cases to
continue the exterior finish, or battering -off, too long, as this ex-
tends the outer case of the metal more than the inner part, and
sometimes separates the two. When imperfect forgings are
broken in the act of being proved, the inner bars are sometimes
found not to be even welded together, and the outside part is a
detached sheath, almost like the rind or bark of a tree.
In twisting the work round the quarter circle, some practice is
called for, in order to retain the rectangular section, and not to
allow it to degenerate into the lozenge or rhomboidal form, which
error it is difficult to retrace.
This indeed may be considered the first stumbling block in
forging, arid one for which it is difficult to provide written rules.
Of course in converting a round bar into a square with the ham-
mer, the accuracy will depend almost entirely upon the change
of exactly ninety degrees being given to the work, and this the
experienced smith will accomplish with that same degree of feeling,
or intuition, which teaches the exact distances required upon the
finger-board of a violin, which is defined by habit alone.
In the original manufacture of the iron, the carefully turned
grooves, a, b, c, of the rollers, page 81, produce the square figure
with great truth and facility ; and under the tilt-hammer the two
opposite sides are sure to be parallel, from the respective parallel-
ism of the faces of the hammer and anvil; and the tietrs, from
constant practice, apply the work with great truth in its second
position. So that under ordinary circumstances the prepared ma-
terials are true and square, and the smith has principally to avoid
losing that accuracy.
First, he must acquire the habit of feeling when the bar lies per-
fectly flat upon the anvil, by holding it slenderly, leaving it almost
ORDINARY PRACTICE OF FORGING.
99
to rotate in his grasp, or in fact to place itself. Next, "he must
cause the hammer to fall flat upon the work : with which view he
will neither grasp its handle close against the head of the hammer,
nor at the - extreme end of the handle, but at that intermediate
point where he finds it comfortably to rebound from the anvil,
with the least effort of, or jar to his wrist. And the height of the
wrist must also be such as not to allow either the front or back
edge of the hammer-face to strike the work first, which would i in-
dent it, but it must fall fair and parallel, and without bruising tho
work.
Figs. 43. 44. 45.
It would be desirable practice to hammer a bar of cold iron, or
still better one of steel, as there would be more leisure for obser-
vation, the indentations of the hammer could be easily noticed ;
and if the work, especially steel, were held too tightly, or without
resting fairly on the anvil, it would indicate the error by addi-
tional noise and by jarring the wrist ; whereas, when hot, the false
blows or positions would cause the work to get out of shape, with-
out such indications.
As to the best form of the hammer, there is much of habit and
something of fancy. The ordinary hand-hammer is represented in
Figs. 43 and 44, but most tool makers prefer the hammer without
a pane, and with the handle quite at the top, the two forming
almost a right angle, or from that to about eighty degrees ; and
sometimes the head is bent like a portion of a circle. Similar but
much heavier hand-hammers, occasionally of the weight of twelve
or fourteen pounds, are used by the spade-makers for planishing ;
but the work being thin and cold, the hammer rises almost ex-
clusively by the reaction, and requires little more than guidance.
Again, the farriers prefer for some parts of their work, a hammer
the head of which is almost a sphere ; it has two flat faces, one
rounded face for the inside of the shoe, and one very stunted pane
at right angles to the handle, used for drawing down the clip in
front of the horse-shoe ; in fact, nearly a small volume might be
written upon all the varieties of hammers.
To return to the forging : the flat face of the hammer should not
only fall flat, but also centrally upon the work ; that is, the centre
of the hammer, in which point the principal force of the blow is
concentrated, should fall on the centre of the bar otherwise that
edge of the work to which the hammer might lean would be the
more reduced, and consequently the parallelism of the work would
100 THE PRACTICAL METAL- WORKER'S ASSISTANT.
be lost. It would also be bent in respect to length, as the thinned
edge would become more elongated, and thence convex; and when
the blows were irregularly scattered, the work would become
twisted or put in winding, which would be a still worse error.
I will suppose it required to draw down (the technical term for
reduction), six inches of the end of a square or rectangular bar of
iron or steel ; the smith will place the bar across the anvil with
perhaps four inches overhanging, and not resting quite flat, but
tilted up about a quarter or half an inch at the near side of the
anvil, as in Fig. 44, but less in degree, and the hammer will be
made to fall as there shown, except that it will be at a very small
angle with the anvil.
Having given one blow, he will as the only change, twist the
work a quarter turn, and strike it again ; then he will draw the
bar half an inch or an inch towards him, and give it two more
similar blows, and so on until he arrives at the extreme end, when
he will recommence ; but this will be done almost in the time of
reading these words. The descent of the hammer, the drawing the
work towards himself (whence perhaps the term), and the quarter
turn backwards and forwards, all go on simultaneously and with
some expedition. At other times the work is drawn down over
the beak iron, in which case the curvature of this part of the anvil
makes it less material at what angle the work is held or the blows
given, provided the two positions be alike.
In smoothing off the work, the position of Fig. 43 is assumed ;
the work is laid flat upon the anvil, and the hammer is made to
fall as nearly as possible horizontally ; a series of blows are given
all along the work between every quarter turn, the hammer
being directed upon one spot, and the work drawn gradually be-
neath it.
The circumstances are exactly the same as regards the sledge-
hammer, which is used up-hand for light work ; the right hand be-
ing slid towards the head in the act of lifting the hammer from off
the work, and slipped down again as the tool descends ; and the
conditions are scarcely altered when the smith swings the hammer
about in a circle, the signal for which is "about sledge;" whereas
when, in either case, the blows of the sledge hammer are to be dis-
continued, the fireman taps the anvil with his hand-hammer,
which is, I believe, an universal language.
In drawing down the tang or taper-point of a tool, the extreme
end of the iron or steel is placed a little beyond the edge of the
anvil, as in Fig. 44 by which means the risk of indenting the
anvil is entirely removed, and the small irregular piece in excess
beyond the taper is not cut off until the tang is completed. Fig.
45 shows the position of the chisel in cutting off the finished ob-
ject from the bar of which it formed a part; that is, the work is
placed betwixt the edge of the anvil, and that of the chisel imme-
diately above the same ; the two resemble in effect a pair of shears
Sometimes the edge of the anvil alone is used for small objects,
ORDINARY PRACTICE OF FORGING.
101
first to indent, and then to break off- the work, but this is likely
to injure the anvil, and is a bad practice.
When it is required to make a set-off, it is done bj placing the
intended shoulder at the edge of the anvil : the blows of the ham-
mer will be effective only where opposed to the anvil, but the re-
mainder of the bar will retain its full size and sink down, as repre-
Should it be necessary to make a shoulder on
sented in Fig. 46.
47
48.
both sides, a flat-ended set hammer, struck by the sledge, is used
for setting down the upper shoulder, as in Fig. 47, as the direct
blows of the hammer could not be given "with so much precision.
In each of these cases some precaution must be observed, as other-
wise the tools, although, so much more blunt than the chisel,
Fig. 45, will resemble it in effect, and cripple or weaken the work
in the corner. On this account the sYnith's tools are rarely quite
sharp at the angles. This mischief is almost removed when the
round fullers, Fig. 48, are used for reducing the principal bulk, and
the sharper tools are only employed for trimming the angles with
moderate blows.
When the iron is to be set down, and also spread laterally, as in
Fig. 49, it is first nicked with a round fuller as upon the dotted
line at a, and the piece at the end is spread by the same tool, upon
a Fis. 49.
the short lines of the object, or parallel with the length of the bar.
The first notch greatly assists in keeping a good shoulder at the
bottom of the part set down, and the lines are supposed to repre-
sent the rough indications of the round fuller before the work is
trimmed up.
There is often considerable choice of method in forging, and the
skillful workman selects that method of proceeding which will pro-
duce the result with the least portion of manual labor. Thus an
ordinary screw-bolt, that I will suppose to measure five-eighths of
an inch in diameter in the stem, and one indi square in the head,
may be made in either of the three following ways adverted to in
the outset :
102
THE PRACTICAL METAL WORKER S ASSISTANT.
First, by drawing-down : — A bar of iron is selected one inch
square, or of the size of the head of the bolt, and a short portion
of the same is set down, according to Fig. 48, by a pair of fullers
that are convex in profile as shown, and also slightly concave upon
the line at right angles to the paper. This prepares the shoulder
or joining of the two dimensions. The bolt is made cylindrical,
and of proper diameter between the rounding tools, Fig. 50 ; and
lastly, it is cut off with the chisel, as in Fig. 45, so much of the
original square bar as suffices for the thickness of the head being
allowed to remain.
Secondly, by jumping: — A piece of bolt-iron of five-eighths of
an inch in diameter, or of the size of the stem of the bolt, is cut
off somewhat longer than the intended length: "a short heat'1 is
taken upon it, that is, the extreme end alone is made white-hot,
then placed perpendicularly upon the anvil, and the cold end is
struck with the hammer as in driving in a nail. This thickens
the metal or upsets it, and makes a thick conical button. The
head is completed by driving the bolt into a heading tool with a
circular hole of five-eighths diameter. The thickened part of the
head prevents the piece from passing through, and the lump is
flattened out by the hammer into an irregular button or disk, which
is afterwards beaten square to complete the bolt. Figs. 51, 52, and
53, explain these processes. The latter is a single tool, but the
heading tool, Fig. 54, with several holes, is also used.
Figs. 50 53
52 51
5(3
55
\J
In upsetting the end of the work, if more convenient, it may be
held horizontally across the anvil and struck on the heated ex-
tremity with the hand hammer; or it can be jumped forcibly upon
the anvil, when its own weight will supply the required momen-
tum. If too considerable a portion of the work is heated, it will
either bend, or it will swell generally ; and therefore to limit the
enlargement to the required spot, should the heat be too long, the
neighboring part is partially cooled by immersing it in the water
trough, as near to the heat as admissible.
ORDINARY PRACTICE OF FORGING. 103
Thirdly, the same bolt may be made by building-up or welding :
— An eye is first made at the end of a small rod of square or flat
iron ; by bending it round the beak iron, as in Fig. 55, it is placed'
around the rod of five-eighths round iron, and the curled end is
cut off with the chisel, as in Fig. 56, enough iron being left in the
ring, which is afterwards welded to the five-eighths inch rod to
form the head of the bolt, by a few quick light blows given at the
proper heat. The bolt is then completed by any of the tools already
described that may be preferred. A swage at the angle of sixty
degrees, Fig. 57, will be found very convenient in forming hex-
agonal heads, as the horizontal blow of the hammer completes the
equilateral triangle, and two positions operate on every side of the
hexagon ; Fig. 57 is essential likewise in forging triangular files
and rods.
Of these three modes of making a bolt, and which will apply to
a multitude of objects somewhat analogous in form, the first is the
most general for small and short bolts ; the second for small but
longer kinds ; and the third is perhaps the most common for large
bolts, although the least secure ; it is used for bolts for ordinary
building purposes, but is less generally employed for the parts of
mechanism.
For works of the same character, in which a considerable length
of two different sections or magnitudes of iron are required, the
method by drawing down from the large size would be too expen-
si VQ ; the method by upsetting would be impracticable ; and there-
fore a more judicious use is made of the iron store, and the object
is made in two parts, of bars of the exact sections respectively.
The larger bar is reduced to the size of the smaller, generally upon
the beak iron with top fullers, and with a gradual transition or
taper extending some few inches, as represented in Fig. 58 ; the
two pieces are scarfed or prepared for welding, but which part of
the subject is for the present deferred, in order that the different
examples of welding may be given together.
The Fig. 58 is also intended to explain two other proceedings
very commonly required in forging. Bars are bent down at right
angles as for the short end or corking of the piece, Fig. 58, by lay-
ing the work on the anvil, and holding it down with the sledge-
hammer, as in Fig. 59 ; the end is then bent with the hand-hammer,
and trimmed square over the edge of the anvil ; or when more pre-
cision is wanted, the work is screwed fast in the tail-vice, which is
one of the tools of every smith's shop, and it is bent over the jaws
of the vice. When the external angle, as well as the internal, is
required to be sharp and square, the work is reduced with the
fuller from a larger bar to the form of Fig. 60, to compensate for
the great extension in length that occurs at the outer part, or heel
of the bend, of which the inner angle forms as it were the centre.
The holes in Fig. 58, for the cross bolts, are made with a rod-
punch, which is driven a little more than half way through from
the one side whilst the work lies upon the anvil, so that when
104
THE PRACTICAL METAL-WORKER'S ASSISTANT.
turned over, the cooling effect of the punch may serve to show the
place where the tool must be again applied for the completion of
the hole ; the little bit or burr is then driven out, either through
the square hole in the anvil that is intended for the bottom tools,
or else upon the bolster, Fig. 61, a tool faced with steel, and having
an aperture of the same form and dimensions as the face of tho
punch.
Figs. 59 58
63
64
65
Fig. 64 shows the ordinary mode of making the square nuts for
bolts. A flat bar is first nicked on the sides with the chisel, ilnn
punched, and the rough nuts if small, are separated and stmig
upon the end of the poker (a slight round rod bent up at the en I),
for the convenience of managing them in the fire, from which they
are removed one at a time when hot, and finished on the triblet,
Fig. 65, which serves both as a handle, and also as the means of
perfecting the holes.
For making hexagon nuts, the flat bar is nicked on both edges
with a narrow round fuller ; this gives a nearer approach to the
hexagon : the nuts are then flattened on the face, punched, and
dressed on the triblet within the angular swage, Fig. 57, before
adverted to. Thick circular collars are made precisely in the same
way, with the exception that they are finished externally with the
hammer, or between top and bottom rounding tools of correspond-
ing diameter.
It is usual in punching holes through thick pieces, to throw a
little coal-dust into the hole when it is partly made, to prevent the
punch sticking in so fast as it otherwise would: the punch generally
gets red-hot in the process, and requires to be immediately cooled
on removal from the hole.
In making a socket, or a very deep hole in the one end of a bar,
*ome difficulty is experienced in getting the hole in the axis of the
bar. and in avoiding to burst open the iron ; such holes are pro-
duced differently, by sinking the hole as a groove in the centre of
a flat bar by means of a fuller ; the piece is cut nearly through from
the opposite side, folded together lengthways, and welded. The
ORDINARY PRACTICE OF FORGING. 105
hole thus formed will only require to be perfected by the introduc-
tion of an appropriate punch, and to be worked on the outside, with
those tools required for dressing off its exterior surface, whilst the
punch remains in the hole to prevent its sides from being squeezed
in : this method is very good.
For punching square holes, square punches and bolsters are
used, and Fig. 62, the split bolster, is employed for cutting out
long rectangular holes or mortises, which are often done at two or
more cuts with an oblong punch.
Mortises, when of still greater length, are usually made by punch-
ing a hole of their full width at each end, and cutting out a strip
of metal between them, by two long incisions made with the rod-
chisel ; at other times one cut only is made, and the mortise is
opened out / this retains all the iron, but makes the ends narrower
than the middle. In finishing a mortise, a parallel plate or drift is
inserted in the slit ; the drift is laid across the chaps of the vice,
whilst the bar of iron lies partly between its jaws, in order that the
blows of the hammer may be effective, on the upper and under
surfaces of the one rib at the same time. The drift serves as a
temporary anvil ; the other rib is completed in the same manner,
and the work is finally closed to its true width upon the anvil, the
drift still lying in the mortise.
When a thick lump is wanted at the end of a bar, it is often
made by cutting the iron nearly through and doubling it backwards
and forwards, as in Fig. 63 ; the whole is then welded into a solid
mass as the preparatory step.
Fig. 66. Fig. 67.
A piece with three tails, such as Fig. 66, is made from a large
square bar ; an elliptical hole is first punched through the bar, and
the remainder is split with a chisel, as in Fig. 67, the work at the
time being laid upon a soft iron cutting plate in order to shield the
chisel from being driven against the hardened steel face of the an-
vil ; the end is afterwards opened into a fork, and moulded into
shape over the beak -iron, as indicated by the dotted lines.
The concave lines about the object are principally worked with
the fuller, or half-round set-hammer ; and in making all the holes,
narrow oval punches are used as described at the commencement,
and the slits are enlarged into circular holes by conical mandrels ;
these bulge the metal out, and the holes are more judiciously formed
in this manner than if the metal were wasted by cutting out great
circular holes, which would sever a large quantity of the fibres and
reduce the strength
106 THE PRACTICAL METAL WORKER'S ASSISTANT.
The mandrels are left in the holes wnilst the parts around them
are finished, which tends to the perfection of both parts ; as the
holes more closely copy the mandrels, and the marginal parts are
better finished when the apertures are for the time rendered solid.
Supposing a hole to be wanted in the cylindrical part of the work
that should be finished between the rounding tools, the mandrel
could not be allowed to remain in ; and therefore a short piece of
iron is forged or drawn down to the size of the hole, cut off in length
to the diameter of the part, and inserted in the hole to preserve it
from being compressed, yet without interference with the completion
of the cylindrical portion; which accomplished, this little bit, called
by the un -mechanical name of a devil, is driven out, unless by a
very careless use of the welding temperature it should have been
•permanently fastened in. Towards the conclusion a long mandrel
is passed through the two holes in the fork of Fig. 66, to show
whether their common axis is at right angles to the main rod,
otherwise the one or other arm is drawn out, or upset, accord-
ing as the work may err in respect to deficiency or excess of
length. Such a piece as Fig. 66, if of large dimensions, would be
made in two separate parts, and welded through the central line
or axis.
Should it happen the two arms are not quite parallel, that is,
when viewed edgeways should they stand oblique to each other, or
to the central bar, an error that could scarcely be corrected by the
hammer alone ; the work would be fixed in the vice with the two
tails upwards, and the one or other of these would be twisted to its
true position by a hook wrench or set, made like the three sides of a
square, but the one very long to serve as a lever ; it is applied
exactly in the manner of a key, spanner, or screw wrench, in turn-
ing round a bolt or screw. The hook wrench is constantly used
for taking the twist out of work, or the error of winding, as the
hammer can only be successfully employed for correcting the cur-
vatures of length.
Some bent objects, such as cranks and straps, are made from bar-
iron, bent over specific moulds, which are sometimes made in pairs
like dies, and pressed together by screw contrivances. When the
moulds are single, the work is often retained in contact with the
game, at some appropriate part, by means of straps and wedges ;
whilst the work is bent to the form of the mould by top tools of
suitable kinds.
Objects of more nearly rectilinear form are cut out of large plates
and bars of iron with chisels ; for example, the cranks of locomotive
engines are faggoted up of several bars or uses laid together, and
pared to the shape ; they are sometimes forged in two separate
parts, and welded between the cranks, at other times they are forged
out of one parallel mass, and afterwards twisted with a hook-wrench,
in the neck between the cranks, to place the latter at right angles.
The notches are sometimes cut out on the anvil whilst the work is
red-hot ; or otherwise bv machinery when in £he cold state.
ON WROUGHT-IRON IX LAEGE MASSES. 107
A very different method of making rectangular cranks and
similar works is also recommended, by bending one or more straight
bars of iron to the form, the angles, which are at first rounded, are
perfected ; by welding on outer caps. In this case the fibre runs
round the figure, whereas when the gap is cut out, a large propor-
tion of the fibres are cut into short lengths, and therefore a greater
bulk must be allowed for equal strength : this method is however
seldom used.
All kinds of levers, arms, brackets and frames, are made after
these several methods, partly by bending and welding, and partly
by cutting and punching out; and few branches of industry pre-
sent a greater variety in the choice of methods, and which call the
judgment of the smith continually into requisition.
CHAPTEK VII.
ON 'WROUGHT-IRON IN LARGE MASSES.
THE manufacture of wrought-iron in large masses cannot boast
of a very early origin. Although we read in the most ancient of
Books that Tubal Cain, before . the Flood, was an instructor of
every artificer in brass and iron, it would doubtless have puzzled
even that great founder of the iron trade, had he been furnished
with an order to make the large masses of wrought-iron required
for a "Niagara," "New Ironsides," "Koanoke," or "Great Eastern"
steam-ship ; and he would have been equally at a loss with many
modern craftsmen, had he been requested to forge a monster gun
or a double-throw crank-shaft for engines of 1000 horse-power.
Were he again permitted to visit the world, the mighty machinery
at work on every hand would compel the admission that his trade
had made great strides during hjs absence. These advances in
the manufacture of wrought-iron in large masses have taken place
almost entirely within the present century, if not, indeed, within
the last thirty years. Up to that period, the improvements upon
Tubal Cain's (we presume original) inventions were of so limited a
nature, that, in the year 1820, the manufacture of a shaft— say of
about 6 inches diameter, and weighing 15 or 20 cwt. — required the
concentrated exertions of a large establishment, and was considered
a vast triumph if successfully accomplished ; whereas we are now
accustomed to forgings of 20 and 30 tons' weight, as matters of
every-day occurrence, scarcely exciting the slightest notice. Nor
do we stop even here : much larger masses will no doubt, ere long,
be manufactured for the construction of iron ships, which in future
years, owing to the increased size and strength of the plates, will
be built upon a scale that would but recently have been deemed
108
THE PRACTICAL METAL-WORKER'S ASSISTANT.
fabulous. This consideration, combined with the requirements of
rapid communication, which demand more colossal engines, call
for renewed energy in conducting this important manufacture.
It may, perhaps, not be out of place to mention here, as a fact
having few parallels in other branches of the industrial arts, that,
almost without exception, all the improvements that have latterly
crowded upon each other in this trade have originated with the
'•'hammermen" or workmen themselves, and have been worked
without even the protection of an exclusive
patent-right.
Our subject naturally divides itself into two
chief heads, viz., the materials of which forgings
are made, and the tools with which the manu-
facture is accomplished. We purpose treating
of the latter first.
DESCRIPTION OF FORGE-TOOLS. — A forge has
necessarily three principal divisions, viz., the
furnace, the crane, and the hammer ; and they
compose the chief fixtures. The furnace (Fig.
68) is, in this country, of the ordinary reverberat-
ing description, strongly bound together with
plates and binders of iron, of a proportionate size
to the description of work intended to be per-
formed. A very great deal more depends upon
the furnace than might be supposed by those
who are not thoroughly conversant with the
practical working of one. Variations in the
slightest detail in their construction
or working are followed by such
great differences in the results, that
even a good and experienced fur-
naceman, if set to manage a strange
i
Fig. 63.
' <
ON WROUGHT -IKON IN LARGE MASSES. / / 109
X/ /';
furnace, will find some difficulty until he has made himself thoroughly
acquainted with its peculiarities.
The selection of a proper description of fire-brick with which to
construct the furnace is a matter of considerable importance. With-
out attempting to enter into the merits of different fire-bricks, we
would observe that the question of expense is infinitesimal when
compared with the consequences of using cheap and inferior bricks,
wliich would be costly at the lowest price, from the great wear and
tear upon them, and from the annoyance and loss caused by the
often-repeated stoppages for repairs. It is, therefore, the wisest
and best economy always to use the very best fire-bricks that
money can procure. In some cases where large work is intended
to be made, a furnace, with a grate at each end, and having the
stack or chimney in the centre, has been tried; but, as it has not
been generally introduced, we presume it possesses few, if any, ad-
vantages over the ordinary furnace. In fact, for the largest forg-
ings that have ever been made, furnaces with single grates have
proved successful, where double-grated furnaces have failed. The
sketch we have given in Fig. 68 is a furnace such as is gener-
ally used, and which is found very effective for the purposes
required.
With anthracite coal, furnaces with closed ash-pits, and blown
with a fan, are used, and which answer very well.
Mr. Mallet, in his work on the " Construction of Artillery,"
page 114, states, that "at length the limit is found when with our
present known modes of working wrought-iron (even with the
heaviest and best appliances) we can no longer add to its size.
The limit is reached by the failure of power to heat the mass, or
the required part of it, to the welding heat. The time required
for the piece to remain in the furnace to effect this, continually in-
creases as its* bulk grows, and with it the sources through which
heat is lost and dissipated; but a certain proportion of iron is
§burned away, or melted from the surface at the part requiring to
be brought to welding, as equals the weight of the 'slab' or mass
laid on, and the labor is then in vain : the work, like that of the
embroidery of Penelope, becomes an endless task, and the limit
has been reached beyond which the piece can be forged no bigger.
The point at which this limit is reached can be stretched a good
deal by the extreme skill of the operative forge man, and the skil-
ful construction of his furnace ; but, however great these may be,
the limit is at length reached by all; and, with our existing tools, in
Great Britain is probably reached in every case at a diameter (of a
cylindrical mass) of about four feet, and about twenty feet in
length."
There is considerable truth and force in these observations as
applied to existing machinery : but the paragraph seems to con-
vey the impression that we are not expected to exceed the limits
laid down by Mr. Mallet. We should be sorry to indorse this
opinion, or to believe that we have even approached the maxi-
110
THE PRACTICAL METAL-WORKER'S ASSISTANT.
mum size in our forgings, having so frequently and so recently
seen that which is in one year deemed impracticable in the manu-
facture of forgings, accomplished with the utmost ease in the suc-
ceeding one ; while the necessary requirements of that year are
again followed by still further improvements, even where inven-
tion and mechanical skill had apparently reached their highest
development. And so it will continue to the end of the chapter.
We might as well attempt to obstruct the progress of the engi-
neer, and say to him, " Thus far canst thou go, but no farther ' ' a-s
attempt to limit the sizes to which forgings may be made in future
years. If larger forgings are required, and money is forthcoming
to pay the cost of their manufacture, the work will not stand still
for the want of workmen to undertake it, or machinery wherewith
to handle it, however large it may be. The only real obstacle to
the production of forgings of larger size is the cost ; the bugbear
set up in the above extract, that more iron is wasted than is added,
being but another mode of accounting for inexperience and bad
workmanship.
CRANE. — The crane is a very useful auxiliary in the working of
the forge. Without its aid it would be impossible to fabricate
those large masses of iron, the almost daily manufacture of which
has ceased to excite surprise at their magnitude.
The crane (Fig. 69), as is well known, is composed, first of a
strong upright, either in-
dependently fixed in a
solid foundation in the
ground, or dependent on
the walls or roof of a
building ; next, of the top
pieces, called " cheeks,"
and the " stays," to which
is attached a winch of
ordinary construction ;
and a strong pair of
blocks, with a chain lead-
ing to the winch. It is
necessary that the blocks
should be capable of
working backward and
forward on the cheeks,
which is technically called
•'' racking out," or " in," from the fact that a rack and pinion-wheel
are generally employed to effect the object. The crane must also
be so placed that the centre is exactly equidistant from the centre
of the furnace-door and the centre of the anvil, its use being to
swing "the piece" from the furnace to the anvil, and vice versa.
Cranes have generally been made of wood, although very few
sorts of wood are capable of resisting the great heat to which
cranes for forging are subjected. Others, hqwever, have lately
69*
"(A)
i
ON WROUGHT-IRON IN LARGE MASSES.
Ill
been made of iron, or of a mixture of iron and wood. Cast-iron,
being comparatively brittle, is decidedly objectionable and unsafe,
in consequence of the great weight they have to bear, and the ex-
cessive jar pf the forge-hammer. There is less objection to wrought-
iron, which, if rightly proportioned, is we believe the best material
-,. ,-ft for the purpose.
HAMMERS. -We
now come to what
is, perhaps, the most
important, or, 'at any
nn I . ^ ^ . v\ I Ir^l I // rate> wtat is con'
L)(\^ _ | I &JJDU/_ sidered the most im-
" portant tool in the
forge, viz., the hammer ; and we purpose giving a slight description
of the various sorts in use at the present time, including the beauti-
ful direct-acting tool known as the Nasmyth or steam-hammer.
We are unable, in the limits of this work, to consider the merits,
or give any description of the various improvements that have
been attempted on the original steam-hammer; some of them* being
confined to matters of detail, while others introduce defects so
palpable, that we gladly return to the original Nasmyth.
The most ancient form of forge-hammer was probably that
technically called the " tennant-helve," Fig. 70, known in France as
the " Marteau frontal," from its being lifted at the front end. This
hammer is a heavy mass of cast-iron, which was lifted by project-
ing arms, fixed in a ring of iron, called the "cam-ring," falling
through a certain space by its own gravity. The pivots behind,
on which it rested, were of a
curved form, to allow its being
easily worked. This was, and
still is in many works, a very
effective tool, performing its work
with regularity, and seldom get-
ing out of order.
The " tennant-helves " being found inconvenient for certain de-
scriptions of work, the " tilt-hammer," Fig. 71, was introduced. In-
stead of being raised at the front end, this hammer is depressed by
« -— !— « cam-ring" from a part projecting behind. It is composed
Fig. 72. °f wood and iron, the shank being of
good tough oak, wedged into a ring
in which it works ; the hammer-head
being also wedged on to the shank.
The shank is surmounted by a beam
of wood, which, acting as a powerful
spring, gives greater force and rapidity
to the blow. This form of hammer
was peculiarly adapted to the " tilting"
of the different sorts of steel.
Another improvement on the original "tennant-helve," was to
Fig. 71,
a similar
112
THE PRACTICAL METAL-WORKER'S ASSISTANT.
Fig. 73.
lift the helve between the head of the hammer and the pivots on
which it worked (Fig. 72), an advantage being thus given to the
hammerman, which the tilt also possesses, by enabling him to go
all round the end of his hammer. But the last and greatest im-
provement was that known to the trade as the " belly-helve," Fig. 73 ;
a not very euphonious name, but one which indicates the nature
of the tool. It was lifted, as its name indicates, under the bottom
part of the helve, by
means of a "bray,"
which could be length-
ened or shortened ac-
cording to the size of
the " piece" to be acted
upon. With some of
the largest size a very
effectual blow is struck with a piece of iron of from 3 feet to 4
feet in diameter — the "helve" being raised, and the "bray" being
lengthened in proportion. This hammer also permits the hammer-
man 1p go completely round his hammer, to inspect the work under
operation. For plain ordinary work it is not surpassed in efficiency,
even by the direct-acting steam-hammer. It is of very great im-
portance that the foundation be perfectly firm, and capable of re-
sisting the force of the blows to which it is subjected. The most
usual way of securing this end, is by placing under the anvil-block
Fig. 74.
— which of itself is
a very massive cast-
ing, weighing, with
the cup upon which
it rests, from twelve
to fifteen tons — a
considerable mass
of timber, carefully
placed and fitted
cross-wise. This
foundation must be
strongly secured, for
unless the anvil-
block is very firm,
a considerable por-
tion of the blow will
be dissipated, and
its value lost.
We come, lastly,
to Nasmy th's steam-
hammer, Fig. 74, a
tool which has de-
servedly come into very general use. Although many of the very
largest forgings have been made by the old-fashioned helves,
especially the "belly-helve" above described; nevertheless, the in-
ON WKOUGHT-IKON IN LAKGE MASSES. 113
yention has been of immense importance, not only to the forge-
masters, but in many other branches of manufacture. The steam-
hammer, like other great inventions, has its faults as well as its
merits. The first great merit of the steam-hammer is, that it is a
simple direct-acting machine, dispensing with much of the cum-
brous wheel- work required with the old helves. It takes up little
room, and requires no " gagger," as the attendant workman is
called, who attends to the hammer. The presence of the " gagger"
we object to, not so much on account of the expense, which is
partly counterbalanced, in the case of the steam-hammer, by the
necessity of employing an engineer ; but on account of the almost
insufferable torture from heat which the "gagger" has to endure:
for if the " gag" is not inserted and the hammer stopped at the
critical moment, a valuable piece of work may be damaged?
Another of the excellences of the steam-hammer is, that the blow
can be varied according to the size of the " piece" under operation,
and the force of the blow required. This is not, practically, such
a great advantage as might at first appear ; but in small works it
is of considerable importance. We would, however, ourselves
rather see the different sizes and classes of work effected under
different sized hammers — with hammers perfectly proportioned to
each description of work. Excepting in very large establishments,
however, where there are a considerable number of hammers em-
ployed, this cannot always be accomplished. The consequence is
that the hammer is used more as a squeezer, frequently crushing
the iron at the heart instead of drawing it in a sound manner under
a hammer proportioned to its size. Where the works, therefore,
are not extensive, or where the number of hammers is limited, the
facility of regulating the stroke by the steam-hammer is an im-
portant advantage in many descriptions of work. Another advan-
tage is, that the hammer is always working parallel with the "piece"
under operation, which is not the case with the old-fashioned helves,
in using which the hammerman has to resort to many ingenious
plans, such as employing thickness pieces, for overcoming this
difficulty.
The hammerman is saved a great deal of trouble in regulating
his tools, by using the steam-hammer. With the old-fashioned
helve, almost every different heat requires an alteration of the tools
employed ; with the steam-hammer there is no necessity for any
such change. This of itself is a considerable advantage. With
the Nasmyth hammer he is also enabled to work on each side of
the hammer, as it can be placed in such a position as to be accessible
on both sides.
There are, however, a few defects even in this beautiful tool ; and
the first which presents itself to our mind is, that the same quantity
of steam is consumed in striking a blow of one foot upon a piece,
say of three feet diameter, as is required for a blow of three feet
upon a piece one foot diameter ; for, the stroke of the hammer being
fixed, the cylinder takes the same quantity of steam in lifting the
THE PRACTICAL METAL-WORKER'S ASSISTANT.
hammer the last foot as it does in lifting it the whole of the stroke.
This might, no doubt, be remedied by some arrangement for raising
or lowering the cylinder according to the height of the " piece"
upon which the blow is to be struck, which would be somewhat
similar to the arrangement in operating with the belly-helve, already
described. Another defect, but one which attempts have been
made to remedy in some modifications of the steam-hammer, arises
from the difficulty of swinging the " piece" to be operated upon,
from the furnace to the hammer, one of the legs of the hammer
being sometimes in the way. This difficulty might be overcome
by allowing the hammer to stand upon one strong leg, which would
in many cases be a considerable improvement. We have, also, a
great objection to the amount of gearing connected with the work-
ing of the valves. They are certainly very beautiful, and of most
ingenious construction : but in all forging tools it is desirable that
the greatest simplicity, combined with the greatest strength, should
always be the first consideration. Arrangements have lately been
made, we believe, for dispensing with these valves, and introducing
in their place a simple balance- valve capable of being worked with
great ease, and not so liable to get out of order.
We have thus given some slight description of the different
hammers employed in a forge. It has not been our intention to-
enter into very minute details upon this subject, nor to advance anj
very decided opinion as to the relative merits of the different imple
ments ; for we are aware that opinions greatly differ upon thes<
points. The improvements that have taken place in this descrip
tion of tools during the last fifteen years have been very great •
but we are prepared to witness still greater developments of me-
chanical application in connection with this branch of the art.
MATERIALS. — We now propose to give a short description of the
materials consumed in the forge, the chief of which are the coals
and the iron. It is of considerable importance that care should be
used in the selection of the fuel for the manufacture of forgings, as
great difference exists in this important mineral, some being very
much more suitable for the manufacture than others. The best
bituminous for the purpose is a strong, dense, durable coal, possess-
ing a good body, and having a dull, dirty appearance. Coal of
this kind with a bright clean look, easily broken, as a general
rule is not suitable. Of course it is desirable that the coal should-
be as free from sulphur as possible, and that it should not contain
any large proportion of those foreign matters which, having an
affinity for iron, fuse on the bars in the shape of clinkers.
We now come to the consideration of the best description of iron
for this manufacture. Scrap-iron is that most generally used ; but,
far from agreeing with the generally received opinion that it is the
best, we think that it is the very worst description of iron for the
purpose ; and for more reasons than one. Engineers usually re-
quire, in their contracts with the forge-master, that their forgings
shall be made from the best scrap-iron ; and it is, of course, the
OX WROUGHT-IROX IX LARGE MASSES. 115
duty of the forge-master to comply with the terms of his instruc-
tions and contract. Let us first endeavor to see how this almost
universal belief in the superiority of scrap-iron has arisen. At
the time when small forgings were first attempted to be made as an
article of commerce, the manufacture of iron was in such an im-
perfect state, and the quality so indifferent, that large quantities of
the best iron had to be imported^rom Sweden and Russia, and for a
long time the scrap-iron was of a quality that could not be approached
by our own iron of that period. Since that time, the use of Eussian
and Swedish iron has been almost entirely discontinued, except for
the manufacture of steel ; the greater part of the scrap-iron now pro-
duced, therefore, is of a very different quality to that formerly known
as best scrap-iron. This material was deservedly considered the most
proper material for the manufacture of forgings that could then be
procured ; but it must be borne in mind that, at the date we speak of,
the forgings were so limited in size that the practical evils result-
ing from the use of scrap-iron, which we are about to explain, were
not so perceptible.
In the ordinary manufacture of bar-iron it is the practice, in most
works, in order to obtain it of the toughest and best description, to
work and re- work it several times over. The number of workings
the iron undergoes is marked by the number of " best" stamps that
it bears, as " best, best best," " treble best," etc., each " best" indicat-
ing a better quality, an extra working, and with a correspondingly
higher price. But this progressive improvement has its limits, as
will be perceived, from a series of experiments which were insti-
tuted by the writer with the object of testing the correctness and
limits of this improvement.
Taking a quantity of ordinary fibrous puddled-iron, and reserv-
ing samples marked No. 1, we piled a portion five feet high, heated
and rolled the remainder into two bars marked No. 2 ; again re-
serving two samples from the centre of these bars, the remainder
were piled as before, and so continued until a portion of the iron
had undergone twelve workings. The following table shows the
tensible strain which each number bore :
No. 1 puddled bar 43,904 Ibs.
" 2 re-heated . . 52,864 "
" 3 ' 59,585 "
" 4 " 59,585 "
" 5 « 57,344 "
" 6 « 61,824 "
" 7 " 59,585 "
"8 " ' 57,344 "
" 9 " 57,344 "
" 10 « 54,104 "
" 11 " 51,968 "
" 12 " 43,904 "
It will thus be seen that the quality of the iron regularly m»
116 THE PRACTICAL METAL- WORKER'S ASSISTANT.
creased up to No. 6 (the slight difference of No. 5 may perhaps be
attributed to the sample being slightly defective) ; and that from
No. 6 the descent was in a similar ratio to the previous increase.
From these experiments it appears that scrap-iron, or any othei
iron, highly refined, is the very worst material for the construction
of large forgings which can be used ; and that if we take, in the
first instance, a strong fibrous fresh-puddled iron, the ordinary
workings required in the process of forging will be sufficient to
improve it to the average maximum of strength required ; whereas
highly refined iron, such as Lowmoor or Bowling, although the
very best description for many purposes, has already reached the
highest point in its strength, from which it is more likely to be
deteriorated by additional workings.
It may then, be asked — how can we hope, with any degree of
success, to manufacture large forgings, which require to be worked
over perhaps a score of times, each working beyond a given num-
ber tending to vitiate the iron ? We can conceive that this deteri-
oration does not penetrate the iron to any great depth ; that few
forgings are heated more than six times in one place before fresh
iron is added ; and that the various layers thus successively added
to the mass protect the under portion from the deteriorating in-
fluences of the successive heatings. It is also to be observed that
any crystallization which might take place, commences from the
outside of the mass ; and as this is the portion which is most
immediately acted upon by the blows of the hammer, the fibre is
elongated in a greater degree, and thus restored to its original
quality. As a proof of this, we may instance the manufacture of
the monster gun, which was built up in seven distinct layers, the
forging of which took seven weeks.
At the meeting of the British Association at Glasgow, in Sep-
tember, 1855, a question was raised in the mechanical section as
to the causes of the deterioration of the metal of which the artil-
lery of the present day was constructed. On this question a long
and interesting discussion ensued, both in reference to the compara-
tive weakness of cast-iron as now produced, and the adaptation of
forged and malleable iron as being stronger and better adapted for
this purpose. The accounts received from the Baltic and Black
Seas of the bursting of guns and mortars of recent construction,
indicated that something was wrong. These failures gave rise to
conjectures on the part of the Government as well as of the public ;
and, in order to trace the cause of this apparent weakness to its
source, an inquiry was institued by the authorities at Woolwich ;
and subsequently the Association appointed a Committee to co-
operate with the Government in the investigation of this very im-
portant question. In order that no time might be lost, the secre-
tary of the section was directed to issue circulars to engineers, iron-
masters, and manufacturers, requesting that they would forward to
the members of the Committee such opinions and observations aa
ON WKOUGHT-IROX IX LARGE MASSES. 117
0
they deemed advisable, in regard to the material itself, and to its
treatment preparatory to the manufacture of ordnance."
It is to be regretted that these circulars were not made more
general, and that more of them were not addressed to practical
forge-masters ; for we observe, among the replies elicited, the
name of one man only practically and intimately connected with
the manufacture of large masses of wrought-iron ; and his reply
is the only one indicating any hope of success in the application of
wrought-iron for ordnance purposes. All the other writers who no-
ticed wrought-iron at all (for many passed it by without the slightest
attention) most unequivocally condemned it, and came to the con-
clusion, that " the tendency to crystallization which the long-con-
tinued heating produces is such, that powerful ordnance -cannot be
manufactured advantageously from malleable iron."*
It was, perhaps, fortunate that the manufacturers of the monster
gun were not aware of the adverse opinions thus pronounced
against wrought-iron for ordnance; otherwise, they might have
been discouraged in their attempt, aud what must now be consid-
ered the successful manufacture of large wrought-iron ordnance
might have been postponed. The following table of the tensile
strength of the iron before it entered into the composition of the
gun ; of the iron cut from it, and as it now is in the gun, both
transverse and longitudinal to the grain ; and of the borings from,
the gun, worked over again in different ways, — tend to show that,
so far from deterioration or crystallization having taken place, the
metal was improved by its long-continued heating and working:
Breaking Sample bars
Experiment Description of Iron. strain in Ibs. Aver- 4 ins. long
per sq. in. age. elongated.
No. 1. Original iron of which the gun was made 48-384 . £ in.
No. 2. Ditto ditto 50-624 49-504 £ in.
No. 3. Cut across the grain from muzzle of gun 41-644 •• f in.
No. 4. Ditto ditto 43-904 .. f in.
No. 5. Ditto ditto 50-624 43-330 | in.
No. 6. Cut with the grain from muzzle of gun 48-384 .. £ in.
No. 7. Ditto ditto 50-624 .. f in.
No. 8. Ditto ditto d2-864 50-624 J in.
No. 9. Borings from gun worked over with eoal 60*584 .. f in.
No. 10. Ditto ditto 62-824 61-704 | in.
No. 11. Borings from gun worked over with charcl. 76-584 76-584 A in.
No. 12. Swedish iron as imported, f Sq. . 60-564 60-584 | in.
From the above experiments it will be seen that the original
iron put into the gun was of no extraordinary strength, which is
accounted for by the fact that it was designedly selected, in conse-
quence of the experiments already quoted, from what is commonly-
known as " No. 2 iron," or iron once worked over from the pud-
dling-process, though of considerable strength and body, and com-
mercially called " common iron." This iron, after seven weeks
heating and shaping into a gun, was, as we have already stated, so
far from being deteriorated by this " long exposure to great heat,"
as to be actually improved in quality ; for we find that the aver-
age of the trials gives an increase of tensile strength from 49*504
118 THE PRACTICAL METAL- WORKER'S ASSISTANT.
Ibs. per square inch to 50-624 Ibs., both trials being longitudinal
with the fibre or grain of the iron.
The strength of the iron across the grain can hardly be regarded
as of much importance, although it exhibits a remarkable amount
'of cohesion, for it was laid in the direction of the strain, and there-
fore the cut transverse to the grain might have been expected to
possess less cohesion in that direction than if the grain had been
placed in its position accidentally.
If we follow this question further, and examine the result of
working over again the borings from this forging, we find that the
tensile strength is increased from 49-504 Ibs. per square inch to
61'704 Ibs. when treated with coke, and 76*584 Ibs. when worked
with charcoal ; and we think with results such as these — without
parallel in any English make of iron, even under the most favor-
able circumstances — we may be allowed to assert that the myth
commonly called " crystallization from long exposure to great
heats," does not apply to the fabrication of this the largest forging
ever made. We have given these details to illustrate and enforce
the preference given to puddled-iron over scrap-iron ; but there is
another very important reason why scrap-iron should not be used
for the manufacture of forgings — scrap-iron is composed of many
various qualities of iron, and all of them have their own special
welding points. When worked together, one portion that is less
refined is too much heated, and consequently deteriorated, before
the more highly refined portions are at a welding heat ; and we
are thus placed in the awkward dilemma of either burning the
one, or of being unable to weld the other. It may be said that
this objection is a mere theoretical one, and that, practically, no
such difficulty exists. This, however, is not the case, for the dif-
ference of temperature at which puddled-iron and a highly-refined
iron weld is very considerable ; although, from the difficulty of
finding a really good pyrometer for these extreme heats, we are
unable to give exact data in degrees. If any proof were required
of this, which is a matter of every -day economy, it is only neces-
sary to inquire into the heating of iron for our rolling-mills. It
is a well-established fact, that, in the mixing of different descrip-
tions of iron in the piles for that purpose, the hardest and most
refined iron is always placed outside, and the puddled or common
iron inside. Were a contrary practice pursued, and puddled-iron
of ordinary quality placed at the outside, and the highly-refined
or scrap placed in the centre of the pile, the outer or puddled-iron
would be wasted and destroyed before the inner portion was suffi-
ciently hot to weld.
We may also call attention to the various qualities found among
scrap-iron, sonue being what are termed "hot-short," and others
'"cold-short." We have before quoted a writer on the subject of
the manufacture of wrought-iron for ordnance, who has stated that
the limit has been reached beyond which forgings cannot be made ;
assigning reasons for those limits according 'to his own ideas and
ON WROUGHT-IRON IN LARGE MASSES. 119
experience, the principal one being the assumed difficulty of heat-
ing such large masses. Now, if we take strong puddled-iron in
place of the " scrap," which has hitherto been the material generally
used, we effect, as we have shown, a saving of say about 20 per
cent, in the heat required to unite soundly the various slabs or por-
tions of which the " piece" is composed ; in other words, by this
simple substitution of the material used,. we increase, to the extent
of about 20 per cent, the suppositions limits of the writer from
whom we have quoted, but the accuracy of whose conclusions we
challenge.
MANUFACTURE. — But scrap-iron, though, as we have endeavored
to show, the worst for our purpose, is the material from which
forgings are generally made ; and we must say a word or two as to
its preparation. It is necessary, in the first place,' that the small
pieces of scrap-iron should undergo a cleaning process. For this
purpose, they are generally placed in a large drum or vessel, which
is caused to rotate at a considerable velocity by machinery ; and
they are thus, to a certain extent, freed from oxide and various
other superficial impurities, that would otherwise injure the material
for forging purposes. In some works, where large quantities of
scrap-iron are consumed for this and other purposes, the scrap is
usually carefully selected ; and none but blue and clean iron, pure
as when it came from the manufacturer's hands, is permitted to be
used for forgings, the rusty and dirty iron being set aside for con-
version to more common purposes, such as the manufacture of
"bar-iron," "grate-bars," etc.
The scrap-iron, having been thus cleaned or selected, is divided
into lumps or masses of various descriptions, by being piled in
quantities generally varying from 100 to 200 Ibs. in weight on a
slate or tile. These piles are charged into a reverberating furnace,
commonly called a "heating" or "balling" furnace. After re-
maining about one hour and a quarter, they are sufficiently heated
to be forged out into slabs or " blooms." The piling of the iron is
an operation requiring considerable skill and experience, for if the
pile is not solidly put together, it will fall down in the furnace, and
perhaps become attached to others. About ten to eighteen of these
piles, according to their size, constitute a charge or " heat ;" and a
good workman will turn out six charges per day, or about 3 tons
10 cwt. to 4 tons. Larger descriptions of slabs are used for many
purposes ; and several of those described are again piled together,
subjected to the heating process, and hammered to the required
shape. In some forges the same workman " shingles" or hammers
his iron from the scrap-pile, and heats it in the same furnace in
which he heats his forgings; but this is by no means a judicious
arrangement. It is much better, especially with large work, that
there should be a division of these operations, and that a certain
number of men, of inferior skill, and consequently of less value,
should heat and " shingle" the iron for the first processes, and de-
liver it to the more highly-paid and skillful hammerman in a further
120
THE PRACTICAL METAL-TVOKKER S ASSISTANT.
advanced and more convenient shape. There is another, and by
no means inconsiderable advantage to be obtained by this arrange-
ment. A much larger amount of work can be accomplished with
the same number of men and tools, than in the case where the two
classes of work are completed by one workman. These slabs vary
in shape and size, according to the nature of the work for which
they are intended ; and are delivered to the hammerman accord-
ingly.
In large forgings, each particular piece requires different treat-
ment, according to the shape and use for which it is intended. On
this depends the question of the best manner of making it. For
instance, a screw-shaft, which is subject to torsion, requires that
the iron should be put together in a manner very different from
the mode in which a crank or cross-head is prepared. We will
take the case of shafts. The most ancient method of forging them
was to take a certain number of slabs or plates of iron, made into
a pile thus, (Fig. 75), and after heating them, to hammer them into
Fig. 75. End View,
Fig. 75. Front View.
the round shape required. As it soon became necessary to make
larger shafts, however, and as this pile could not conveniently be
increased, an improvement was introduced, which consisted in
taking a pile of slabs as before, and drawing a portion only of the
mass into the shape required (see Fig. 76), leaving a lump on the
end on which to place more slabs as needed ; then drawing a little
more at A to the required shape, adding more and more slabs as
occasion required. This method is still practised at many works,
and with considerable success ; but it requires the utmost care and
circumspection, both in regard to workmanship and materials.
This is the method by which shafts are generally made in the north
of England and Scotland, and in America.
Fig. 76. Front View.
Another plan is to lay up a faggot of square bars sufficient to
make the required shaft (Fig. 77). This is a considerable improve-
ment upon the slab-plan, there being much less risk of false weld-
ON WROUGHT-IROX IX LARGE MASSES.
121
ings and careless workmanship ; and for this reason, when slabs
are used, if the heat has not been sufficient to give a perfect weld
to the iron, or if any oxide or dirt should intrude, the flaw or de-
fect would, run more across the shaft than in the faggot, where
indeed any flaw from such causes would run longitudinally with
the shaft, and consequently would not interfere in any thing like
the same degree with its strength. But this method also requires
great care and attention ; for if the faggot of square bars be made
too large at one heat, the interior of the mass cannot be sufficiently
Fig. 77. Front view.
heated to allow of the iron boing welded at tha centre. I have
Fig. 77. End view.
Fig. 78. End view.
often seen a broken steamboat shaft which has never been united
Fig. 78. Front view.
at all at the heart, the bars from which it was made being in the
same shape and state as when they were placed in the faggot. To
avoid this great evil it is necessary to be especially careful not to
pack faggots too large at once, but to make, in the first instance, a
moderate-sized one, which, after being worked perfectly sound, has
another layer of bars packed round it, and so on with further
layers, until the necessary size is attained with perfect soundness.
Thus Fig. 78, A being the original faggot after it has been made
sound and solid, has the bars, as shown, packed round it ; it is then
again heated and hammered into the required shape.
The third method of manufacturing large shafts is commenced
122 THE PRACTICAL METAL-WORKEli'S ASSISTANT.
by making a round core or heart, B, and taking bars of a V form
to pack round it (Fig. 79). This is a method of forging railway
Fig. 79. T'nd view. ax^es which is frequently adopted. It was also
the method adopted, with some variations, in
forging the monster gun at the Mersey Iron
Works. In a previous page we have given the
tensile strength of the iron before it was forged
into the gun, and its condition after undergoing
that process ; and it may be satisfactory if we
give some details of the manner in which this
large forging was worked.
We have already stated that it was built up in seven distinct
Fior. 79. Front view.
layers or slabs, and that the forging occupied seven weeks. Nor
will this time seem unreasonable when its dimensions and weight
are remembered. The chief points to be considered by the de-
signer of the gun were, to obtain sound weldings ; to place the
iron, with its fibres, in the proper direction for resisting the most
severe strains to which it could be exposed ; and to take care that,
while working one part of the forging, other portions were not
wasted under the action of the furnace by burning or crystalliza-
tion. The first operation was to prepare a core of suitable dimen-
sions, and nearly the whole length of the gun. This was done by
taking a number of rolled bars, about six feet in length, welding
them together, and drawing them out until the proper length was
obtained. A series of V -shaped bars were now packed round the
core, the whole mass heated in a reverberatory furnace, and forged
under the largest belly-helve hammer. Another series of bars were
now packed on, and the mass was heated again, and worked per-
fectly sound. Another longitudinal series of bars were still re-
quired over the whole length of the forging, which were added ;
and the mass now presented a forging about fifteen feet in length
and thirty-two inches in diameter, but requiring to be augmented
to forty-four inches at the breach, tapering down to twenty-seven
inches at the muzzle. This was accomplished by two layers of
iron, placed in such a manner as to resemble hoops, laid at right
angles to the axis of the mass ; and, after two more heatings and
careful welding, the forging of the gun was completed. After
each important addition, a " securing" heat was given to prevent
flaws. It would be foreign to our purpose here to deal with this
implement otherwise than as a mass of forged iron. Its di-
ON WKOUGHT IRON IN LARGE MASSES. 123
mensions, as given by Captain Vandaleur, in his report, are as
follow :
Ft. Ins.
Length 15 10
Diameter at base 3 7J
Diameter at muzzle 2 3|
Diameter at trunnions 3 3 J
Length of bore 13 4
Diameter of bore 0 13*05
Its present weight is 21 tons 17 cwt. 1 qr. 14 Ibs. The original
weight, before boring, was 25 tons. The furnace employed was a
reverberatory one ; and the hammer, as we have seen, was the
great belly-helve tilt-hammer, weighing 10 tons. As already inti-
mated, the iron bored out of the gun was tough, sound, and per-
fectly homogeneous, some of the borings being curled like a watch-
spring seven times round ; and, when worked up again, it bore the
test applied to prove its strength, as reported at page 117 ; and
Messrs. Horsfall have the satisfaction of having produced a forging
which the scientific world had hitherto deemed impracticable.
Shafts have sometimes been made after another method, which
we consider very injudicious. Many specimens of this mode of
manufacture have come under the notice of the writer in the shape
of broken shafts, where the unsoundness, arising from the method
of working adopted, has been so great as to make it a matter of
surprise that the shaft had done any duty at all.
The method in question was to forge four large square bars,
proportioned, of course, to the size of the shaft required ; packing
them together (Fig. 80). This faggot was of such immense size,
Fig. 80. Front view.
that the furnace and hammer employed were altogether insufficient
to produce sound work. As a Fig. so. End view. Fig. si.
necessary consequence, when the
shafts so made were broken, the
fracture had an appearance sim-
ilar to Fig. 81, being only welded
on the circumference ; while the
four fissures at the centre were sufficient, in many cases, to receive
a man's hand, while a rod of iron could be inserted from one end
to the other.
CRYSTALLIZATION. — A great deal has been said and written with
reference to a supposed deterioration, or, as it has been called,
'' crystallization" of iron, when rolled in large masses, from long-
continued and frequent heatings. It has also been asserted that the
124 THE PRACTICAL METAL WORKER'S ASSISTANT.
iron, while lying in the furnace, is continually attracting carbon
from the grate, until, in course of time, it becomes carburetted, — •
that is, reconverted into pig-iron. When this theory was first pro-
pounded, the writer determined to test its accuracy ; and that in
the presence of the gentlemen by whom it had been promulgated.
A small knob, or corner, was accordingly detached from a large
forging which had been over-heated or burnt. It broke off with
a large flaky appearance very similar to some descriptions of lead
ore. This was pronounced to be very similar in its nature to cast-
iron, and in the so-called crystallized state. Proceeding to the
smiths' department, the iron was heated in the fire, and drawn
down to about three times its original length. It worked well
under the hammer ; and when broken again in the usual way, was
as beautifully fibrous as the iron from which it was originally made.
This experiment led to the conclusion that the iron acted upon was
very different in its nature from cast-iron, and certainly failed in
sustaining the crystallization theory.
It may be well, however, in the first place, to consider what is
the meaning attached to this term " crystallization." It has been
generally used to signify that the structure or composition of the
iron has entirely changed its character and assumed a new form.
Mr. Mallet, in page 110 of his work before quoted, thus describes
this change :
" With the same iron and the same volume of forging, however,
the size of the crystals appears to be large and more developed in
proportion to the time that the mass is maintained hot and in pro-
cess of forging. This time is necessarily greater as the mass is so;
and as the operation of reducing it to the required form is more
complex or laborious. In fact, as in cast-iron, we saw that the
crystals were larger the longer the mass required to cool ; so in
wrought-iron, they are larger the longer the mass is kept hot : and
thus it happens that in very large and massive forgings, requiring
often to be maintained perhaps for weeks, at temperatures varying
from welding-heat down to dull redness, crystals are developed
within the mass of a size tending materially to diminish, in some
places, the average cohesion of the iron, where their planes of
cleavage produce partial planes of weakness. The size of these
crystals is occasionally surprising ; the broadest and flattest plane?
of cleavage frequently running in the direction in which surfaces
of the integrant slabs, or portions of iron of which the mass has
been formed, have been welded together. The author has observed
crystals to deposit flat planes as large as the surface of a half-crown
piece in forgings under seven tons weight."
We have little doubt that in many instances this statement is
perfectly correct ; we, however, at the same time declare our belief
that cases are referred to where the greatest carelessness and inat-
tention on the part of the workmen have been exhibited. We think,
moreover, that some experiments which have taken place, and others
which are still making, under the direction, of Mr. Mallet, will
ON WKOUGHT IRON IN LARGE MASSES. 125
induce him to alter his opinion on this point. To one of these we
may here allude in support of this view : a sample bar has been
planed out of the body of a large wrought-iron mortar piece made
for him, and the sample shows a highly fibrous development, very
different in appearance from the specimens described by Mr. Mallet
in the above extract — a description, be it observed, which may be
at any time observed in a forge on examining a piece of burnt iron
or in an exposed corner which has been subjected to very great but
not necessarily continued heat.
It seems to us that all wrought-iron is, more or less, crystalline
in its structure; and that the difference between what we call
fibrous and crystallized iron only consists in the degree of fineness
in the crystals, and perhaps in the manner in which they are laid
together ; the presence, also, of foreign matters, such as silicon, in
some form, may also have its influence. Whatever the cause may
be, however, it is known that a piece of good fibrous iron will break,
under the smith's hammer, with a long silky appearance ; if suddenly
fractured by an irresistible blow, the same piece of iron will break
crystalline, but the crystals will be very fine and close, and of a
good color.
In some experiments made at Woolwich, in the year 1842, to
test the effect of shot against wrought-iron plates, and determine
whether wrought-iron was a suitable material for ships of war, it
was found that the toughest and most fibrous plate-iron, when
struck by shot, was instantaneously crystallized ; while the pieces
struck out were so hot, that the fragments, even after passing a
considerable distance through the air, could not be handled with
the naked hand ; in many cases the fracture had that blue appear-
ance, which is indicative of considerable heat.
A 68-pounder wrought-iron gun burst with the first charge at
Woolwich, on the 12th of July, 1855 ; on examination, the iron
was pronounced to be crystallized, and its nature changed, by long
exposure to great heat. This crystalline appearance was, most
probably, the result of the very sudden disruption, as in the ex-
periments with the iron plates ; and, according to our view of the
case, is traceable to bad workmanship. A considerable portion of
the bars of which the forging was composed had never been welded
at all ; and no doubt the fracture commenced with these false weldings.
The crystalline appearance, where the iron was torn from the solid
mass, arose, at any rate, to a great extent, from the sudden fracture.
Other causes, no doubt, assisted ; among which the selection of iron
too highly-refined may be included. From this crystalline ap-
pearance, the authorities of the Ordnance Department arrived at
the conclusion, that large masses of iron, from long-continued heat
ing, have a tendency to crystallize, and lose the properties peculiar
to wrought-iron. Acting on this hypothesis, they put a stop to
what were called "Nasmyth's experiments" at Patricroft, pro-
nouncing the manufacture of a wrought-iron gun of large size im-
possible— a theory which the successful manufacture of a much
126 THE PRACTICAL METAL-WORKERS ASSISTANT.
larger piece lias since practically shown to be incorrect. As we
have before shown, a bar of iron, planed transversely from a piece
cut off the end of the gun, broke with a fibrous texture, and with
a very slight tendency to crystallization ; and that crystal by no
means of a large character. This sample had never been treated or
altered in the slightest degree since it was cut off the gun, and it
would be pronounced "excellent best iron." A portion of this was
afterwards rolled down to three-eighths of an inch round bar-iron,
and it was bent cold in all ways without giving way in the slightest
degree.
Having thus endeavored to explain the meaning of the term
" crystallization," let us now endeavor to trace the causes which
produce this result.
The change in the structure of the mass of iron, when it occurs
during the process of heating, is usually produced from the furnace
being urged to a much greater heat than is necessary for welding
the iron ; in fact, the outside first, and, if the heat be not checked,
the whole of the mass, is reduced to a pasty or partially fluid con-
dition. The structure of the iron is thus entirely changed ; and in
the process of cooling the mass, crystallization takes place in £ne
same manner as with other substances which crystallize in passing
from the fluid to the solid state. Under these circumstances, the
iron may be injured — in other words, it may be burned : but we
are not to suppose that such a result is either inevitable or by any
means common ; on the contrary, the heat necessary to produce the
evil is with difficulty obtained in our ordinary furnaces, under the
most favorable circumstances.
Some years ago the experiment was tried at the Mersey Steel
"Works of fusing wrought-iron, with the idea of casting it into such
shapes as " cranks," " cross-heads," and other forms required by
engineers. They succeeded perfectly in obtaining excellent castings :
but it was found that the deterioration of the structure of the iron
in passing from the fluid to the solid state was such, that the work
produced had little more strength than ordinary cast-iron. Of
course, the manufacture was at once given up. But in the appear-
ance of the fracture of the ingots resulting from Mr. Bessemer's
experiments at Baxter-house, there was a great similarity between
it and the results obtained in melting scrap wrought-iron.
Mr. Mallet, in his work (Note K, page 251), says:— " Late ex-
perience has shown me that in very large cylindrical masses of
forged wrought-iron (i. e. of three feet diameter and upwards),
amongst the other abnormal circumstances involved in their pro-
duction, is that of their frequently rending or tearing internally in
planes nearly parallel with, and about the axis, though not always
in it, presenting a character similar to those described in section
217 ; the cause appears to be, that in the progress of cooling such a
mass the exterior cools first and becomes rigid, while the internal
portions are still red-hot and soft. The external parts contract as
they cool, but they already grasp, in perfect contact, the still hot
OX WROUGHT IRON IX LARGE MASSES.
127
Fig. 82.
interior ; the exterior therefore cannot contract fully, but becomes
solid under constraint circumferentially, partly itself extended in
virtue of its compressing the still hot and soft interior. The latter
at length also becomes cold and rigid ; but its contraction is now
resisted by the rigid arch of the exterior with which it is surrounded.
The contraction of the interior, therefore, is limited to taking place
radially outwards from the centre ; and thus the mass rends itself
asunder in some one or more planes parallel to the axis of the
cylinder.
"Inacylindric mass of forged iron, varying from 24 to 36 inches
in diameter, rents of 18 inches in width
across a diameter were found, with jag-
ged counterpart surfaces clearly torn as-
under, and about f ths of an inch apart at
the widest or central part ; the fact is
most instructive as to the enormous in-
ternal strains that must exist from like
causes in cast-iron guns and mortars of
larje size."
We give a sketch (Fig. 82) of the form
of this forging, showing the faults or "fis-
sures" that were found in it, and which
no doubt took place from contraction after
the piece had left the hammerman's hands
perfectly sound.
When the forging was cooling, the
part D would of course cool first; and as
there was no great differential diameter
between D and B, the differential con-
traction was not greater than the elas-
ticity of the materials permitted: but the
sudden and great difference in the diam-
eters B and A caused the forging at B
to be comparatively cool; whilst the Urg-
ing at A had very considerable heat, the
parts of the forging at B and D, being
nearly cold, became rigid and unalter-
able, constituting a very strong arch,
which prevented the forging from con-
tracting in a regular manner.
If this forging had been of one uni-
form cylindrical shape, these fissures
would not have taken place, as the con-
traction would have been uniform throughout, at the same time the
conducting power of iron is sufficient to allow of the heat passing
from the interior to the outside with sufficient rapidity to prevent
any fissure or unsoundness taking place in the forging.
Mr. Mallet proceeds to say — " It is probably from this cause that
more or less hollo wness is found in the centre of almost every. large
128 THE PRACTICAL METAL-WORKERS ASSISTANT.
forging, greater in proportion as the forging is larger. The difficulty
is one not easily overcome. Very slow, and, as far as possible, uni-
form cooling of the whole mass in an annealing oven, suggests itself
as one remedy; but this has disadvantages in enlarging the crystal-
line development of the metal, or providing a central cylindrical
opening, so as to cool the circumference and the centre together."
Here, at last, we come to a tangible danger to be feared in the
manufacture of large forgings, provided that due care and atten-
tion be not paid to its proper manipulation. But this danger is
also common to castings, being created not by equal, but by dif-
ferential contraction. There is nothing more to be dreaded in
casting metals of any sort, but more especially those in which the
contraction is great, than that any part of the casting should be
suddenly reduced or increased in size. When this is the case,
what the founders call " a draw" evidently takes place ; and the
same result is observed in large forgings, from the cooling of the
smaller portions before the larger. In such a case as this, let us fol-
low the practice of the engineer and founder, who, from experi-
ence and long practice, discourage such shapes as are found im-
practicable, and make such modifications in their plans as shall do
away with these differential results.
Whilst Mr. Mallet's work was passing through the press, and
without any communication from him, the maker of the forgings
he mentions, after three failures, overcame the difficulty in the
manner proposed : viz., by making a cylindrical opening in the
centre, which allowed the interior of the forgings to cool as rapidly
as the external ring, and which permitted the necessary contrac-
tion without producing fissures. To endeavor to overcome the
difficulties incident to an important manufacture, which is still in
its infancy, appears to be much preferable to the theory and max-
ims of the "How-not-to-do-it" school, who would sit quietly down
under a difficulty Avithout attempting to remove it.
In the Report, made by a Committee of the Franklin Institute,
on the bursting of the wrought-iron gun on board the United
States steam -frigate "Princeton," the following facts were elicited:
"1. The iron of which the gun was principally made was capa-
ble of being rendered of a good quality by sufficient working.
"2. From the state in which the iron was put into the gun, it
was not in a proper condition for the purpose to which it was ap-
plied.
" 3. The metal, as it existed in the gun, was decidedly bad.
"4. As to the manufacture of the gun, the welding was imperfect.
"These facts relate exclusively to the gun submitted to the ex-
amination of the committee, and they are derived from immediate
experiments and observation. But besides giving these to the
public, the committee felt themselves bound to express the opinion,
that in the present state of the arts the use of wrought-iron guns
of large calibre, made on the same plan as the gun now under ex-
amination, ought to be abandoned for the following reasons :
OX WBOUGHT-IROX IN LARGE MASSES. 129
" 1. The practical difficulty, if not impossibility, of welding such
a large mass of iron, so as to insure perfect soundness and uni-
formity throughout.
" 2. The uncertainty that will always prevail in regard to imper-
fections in the welding. And,
"3. From the fact that iron decreases in strength from long ex-
posure to the intense heat necessary in making a gun of this size,
without a possibility of restoring the fibre by hammering with the
hammer at present in use in this country. At the same time the
committee would not wish to be understood as expressing any
opinion whether the construction of a safe wrought-iron gun upon
some other plan is practicable or otherwise, in the present state of
the arts, inasmuch as this subject has not been referred to them by
the Department."
We are sorry that Mr. Mallet thinks it necessary to add to this
Report, which he quotes at length in his valuable work on the
" Construction of Artillery," the following remarks :
" Nothing can more strikingly show the deteriorating effects of
forging in large masses (however done) upon the tenacity of
wrought-iron, than the fact of the preceding Report, nor the un-
certainty of the process as respects welding. That the latter diffi-
culty may be greatly mitigated (though it cannot be removed) by
pre-eminent skill on the part of the hammerman, is proved by the
success of the Mersey Steel Company in the duplicate perfected by
them of the gun which failed for the ' Princeton,' and still more
in the stupendous and apparently perfect forging they have now
almost finished into a gun for the Government, no doubt by far
the largest ever made in one piece, being 13 J feet length of chase,
13 inches calibre, 14 or 15 inches thick at the charge, and about 9
inches at the muzzle, a solid shot of which will weigh 300 Ibs."
Mr. Mallet thus gives the weight of his authority (for which we
entertain the greatest respect) to sentiments which, in our opinion,
hardly need any further refutation than the facts which he himself
mentions.
The several failures in the manufacture of wrought-iron guns
should not be a matter of surprise ; for it is hardly reasonable to
expect immediate success in any new fabrication. How many
failures, it might be asked, occurred before cast-iron guns were
brought to the comparative perfection they have now reached?
When we consider that an attempt has been successfully made to
construct two of the largest guns ever attempted of wrought-iron,
without having had any failure to record, we think it hardly pro-
bable that failure should occur where sufficient skill in workman-
ship is used, and with it added experience. It would, indeed, be
somewhat strange, if, with additional experience, less successful
results were to be obtained than in the first comparatively novel
experiments.
One of the most common forms of real crystallization results
from what is technically called " hammer-hardening." In the yeai
9
130 THE PRACTICAL METAL-WORKER'S ASSISTANT.
1854, at the meeting of the British Association in Liverpool, a
paper was read by the writer of this article on the subject of crys-
tallization of iron under certain circumstances. He selected a
piece of good, tough, fibrous bar-iron, which he tested by treating
in the usual manner. He then heated it to a full red heat, and
hammered it by light, rapid, tapping blows, until it was what is
called " black-cold." After it was allowed to cool, he again broke
it, and found that the structure of the iron was entirely changed ;
and that, instead of bending nearly double without fracture, and,
when the fracture did occur, breaking with a fine, silky fibre, an
entire alteration had taken place, and the bar was of a rigid, brit-
tle, sonorous character, incapable of bending in the slightest de-
gree, but breaking with a glassy, crystallized appearance. By
simply heating the bar to the same red- heat again, the fibre was
restored exactly as before. This change in the structure of iron
has been observed in railway axles and chains ; and we believe
that it is now customary, in some manufactories, to anneal such
articles as are exposed to any jar or percussion, at regular periods,
and with a beneficial result. Now this crystallization is particu-
larly to be dreaded in forgings, for, unless great care is used, this
error of " hammer-hardening" will often take place — sometimes
from the vanity of the forge-man, who is naturally desirous to turn
out a pretty well-finished forging ; at other times, as is more gen-
erally the case, from the requisition of the engineer, who, without
thinking of the result, wishes to have his forging delivered to him
as nearly as possible to the finished size ; and when, as is often the
case, a very small allowance or margin is given between the forged
and finished dimensions, the forge-man is under the necessity of
working his iron much colder than is consistent with a due regard
to strength. It is very true that some forge-men will work much
nearer to the sizes given them than others, and still avoid the dan-
gerous error of cold-hammering; but when certain dimensions are
a sine qua non, inferior workmen, to keep anywhere near the mark,
must " cold-hammer" their work ; for none but a first-rate work-
man, and one who has every confidence in his own powers, dare
bring his iron down to the required size at full heat.
Some engineers, and we have known instances among the most
eminent, in ordering their forgings, have made the remark — " Pray
take care not to finish the work too cold, for we do not care for a
fine polish to our forgings ;" and this language we would urge all
engineers to use. Such an instruction shows a true appreciation
of the danger of cold-hammering, and a knowledge of his craft,
which it is the object of this work to convey to all. But while we
have a very strong objection to cold-hammered forgings, we should
be sorry to be understood as encouraging that slovenly description
of forging, which leaves the pieces so clumsy and unsightly as to
require more than a necessary amount of cutting or turning. This
is an error that ought also to be avoided. If proper care and
attention were paid to the quality of the material used, as well as
GENERAL EXAMPLES OF WELDING. 131
to the workmanship, we should have fewer break-downs in our
sea-going steamers, and might, with perfect safety and great advan-
tage, reduce the weight of those parts that are made of wrought-
iron. In the selection of forgings, the cheapest are generally a
long way from being the least costly ; for the extra weight of mate-
rial used, often brings the actual cost up to a level with the dearer,
but better-finished and lighter forgings. Where cheapness of first
cost is the rule, though accepted as the cheapest, it will, in all
probability, be the dearest in the end.
In concluding this chapter, we would observe, that the opin-
ions and facts here developed (although the result of long practical
experience) have been put together at a short notice, during the
pressure of onerous business engagements, which permitted but
little time to be devoted to the subject. The author does not for a
moment pretend to treat this important subject in the scientific
manner that it deserves ; but, when requested, he gave his humble
assistance to further, though in a slight degree, the development
of knowledge on a subject which has hardly ever received the
attention of those practically competent to write upon it; but
which, he is convinced, is of great and growing importance to the
country, as a national manufacture in which it stands proudly pre-
eminent.
Should, however, the few remarks which we have put together
awaken more inquiry, and further investigation of the subject, by
those who have leisure and ability to pursue it, the author will re-
joice that his humble endeavors have not been altogether in vain.
CHAPTER VIIL
GENERAL EXAMPLES OF WELDING.
THE former illustrations of forging have been to some extent de-
scriptive of such works as could be made from a single bar of
iron, on purpose that the examples to be advanced in welding or
joining together two pieces of iron by heat, technically called
"shutting together" or " shutting -up,n might be collected at one
place.
There are several ways of accomplishing this operation, and
which bear some little analogy to the joints employed in carpentry ;
more particularly that called scarfing, used in the construction of
long beams and girders by joining two shorter pieces together end-
ways, with sloping joints, which in carpentry are interlaced or
mortised together in various ways, and then secured by iron straps
or bolts. In smith's work, likewise, the joinings are called scarfs,
but from the adhesive nature of the iron when at a suitable tern
132
THE PRACTICAL METAL-WORKER'S ASSISTANT.
perature, the accessories called for in carpentry, such as glue, bolts,
straps and pins, are no longer wanted.
The example, Fig. 58, was left unfinished, but we will proceed
to show the mode of joining the two cylindrical ends of the work.
The scarfs required for the "shut" are made by first upsetting or
thickening the iron by blows upon its extremity, to prepare it for
the loss it will sustain from scaling off, both in the fire and upon
the anvil, and also in the subsequent working upon the joint. It
is next rudely tapered off to the form of a flight of steps, as shown
in Figs. 83 and 84, and the sides are slightly beveled or pointed,
as in Fig. 84, the proportions being somewhat exceeded to render
the forms more apparent.
87
84
86
The two extremities are next heated to the point of ignition ;
and when this is approached, a little sand is strewed upon each
part, which fuses and spreads something like a varnish, and parti-
ally defends them from the air ; the heat is proper when, notwith-
standing the sand, the iron begins to burn away with vivid sparks.
The two men then take each one piece, strike them forcibly across
the anvil to remove any loose cinders, place them in their true
positions, exactly as in Fig. 83, and two or three blows of the
small hammer of the principal or fireman stick them together; the
assistant then quickly joins in with the sledge-hammer, and the
smoothing off and completion of the work are soon accomplished.
It is of course necessary to perform the work with rapidity, and
literally " to strike whilst the iron is hot ;" the smith afterwards
jumps the end of the rod upon the anvil, or strikes it endways
with the hammer ; this proves the soundness of the joint, but it is
mostly done to enlarge the part, should it during the process have
become accidentally reduced below the general size. The sand
appears to be quite essential to the process of welding, as although
the heat might be arrived at without its agency, the surface of the
metal would become foul and covered with oxide when unprotected
from the air — at all events common experience shows that it is
always required. The scarf joint, shown in Figs. 83 and 84, is
commonly used for all straight bars, whether flat, square or round,
when of medium size.
GENERAL EXAMPLES OF WELDING. 133
In very heavy works the welding is principally accomplished
within the fire : the two parts are previously prepared either to the
form of the tongue or split joint, Fig. 85, or to that of the butt joint,
Fig. 86, and placed in their relative positions in a large hollow
fire. When the two parts are at the proper heat, they are jumped
together endways, which is greatly facilitated by their suspension
from the crane, and they are afterwards struck on the ends with
sledge-hammers, a heavy mass being in some cases held against
the opposite extremity to sustain the blows ; the heat is kept up,
and the work is ultimately withdrawn from the fire, and finished
upon the anvil.
The butt joint, Fig. 86, is materially strengthened, when, as it is
usually the case for the paddle shafts of steam vessels and similai
works, the joint whilst still large is notched in on three or four
sides, and pieces called stick-in pieces, dowels, or charlins, one of
which is represented by the dotted lines, are prepared by another
fire, and laid in the notches ; the whole, when raised to the weld-
ing heat, is well worked together and reduced to the intended
size ; this mingles all the parts in a very substantial manner. For
the majority of works, however, the scarf joint, Fig. 83, is used,
but the stick-in pieces are also occasionally employed, especially
when any accidental deficiency of iron is to be feared.
When two bars are required to form a T joint, the transverse
piece is thinned down as at a, in Fig. 87; for an angle or corner the
form of b may be adopted ; but c, in which each part is cut off ob-
liquely, is to be preferred. The pieces a, b, c, are represented up-
side down, in order that the ridges set down on their lower sur-
faces may be seen. In most cases when two separate bars are to
be joined, whatever the nature of the joint, the metal should be
first upset, and then set down in ridges on the edge of the anvil,
or with a set hammer, as the plain chamfered or sloping sur-
faces are apt to slide asunder when struck with the hammer, and
prevent the union. When a T joint is made of square or
thick iron, the one piece is upset, and moulded with the
fuller much in the form of the letter ; it is then welded against
the flat side of the bar : such works are sometimes welded with
dowel or tenon joints, but all the varieties of method cannot be
noticed.
There are many works in which the opposite edges, or the ends
of the same piece, require to be welded. In these the risk of the
two parts sliding asunder scarcely exists, arid the scarfs are made
with a plain chamfer, or simply to overlap or fold together with-
out any particular preparation.
Of the last kind Fig. 63 may be taken as an example, in which
the parts have no disposition to separate. In this and similar cases
the smith often leaves the parts slightly open, in order that the
very last process before welding may be the striking the whole
edgeways upon the anvil, to drive out any loose scales, cinders or
sand, situated between the joints : which if allowed to remain
134 THE PRACTICAL METAL-WORKER^ ASSISTANT.
would be either inclosed amidst the sound parts of the work, or
would partially prevent the union.
In works that have accidentally broken in the welded part, the
fracture will be frequently seen to have arisen from some dirty
matter having been allowed to remain between them, on which
account, shuts or welded joints extending over a large surface are
often less secure than those of smaller area, from the greater risk
of their becoming foul. In fact, throwing a little small coal be-
tween the contiguous surfaces of work not intended to be united,
is a common and sometimes a highly essential precaution to pre-
vent them from becoming welded.
The conical sockets of socket chisels, garden spuds, and a variety
of agricultural implements, are formed out of a bar of flat iron,
which is spread out sideways or to an angle, with the pane of the
hammer, and then bent within a semi-circular bottom tool also, by
the pane of the hammer, to the form of Fig. 88 ; after which the
sockets are still more curled up by blows on the edges, and are
Figs. 88
perfected upon a taper-pointed mandrel, so that the two edges
slightly overlap at the mouth of the socket, and meet pretty uni-
1 formly elsewhere, as in Fig. 89, and lastly, about an inch or more
at the end is welded. Sometimes the welding is continued through-
out the length, but more commonly only a small portion of the
extremity is thus joined, and the remainder of the edges are drawn
together with the pane of the hammer.
In making wrought-iron hinges, two short slits are cut length-
ways and nearly through the bar, towards its extremity. The iron
is then folded round a mandrel, set down close in the corner, and
the two ends are welded together. To complete the hinge, it only
remains to cut away transversely, either the central piece or the
two external pieces to form the knuckles, and the addition of the
pin or pivot finishes the work.
Musket barrels, when made entirely by hand, were forged in the
form of long strips about a yard long and four inches wide, but
taper both in length and width, which were bent round a cylin-
drical mandrel until their edges slightly overlapped. They were
then welded at three or four heats by introducing the mandrel
within them instantly on their removal from the fire at the proper
heat, in order to prevent the sides of the tube from being pressed
together by the blows of the hammer.
They have been subsequently and are now universally welded
by machinery, at one heat ; and whilst of the length of only one
foot, as on removal from the fire the mandrel is quickly intro-
duced, and the two are passed through a pair of grooved rollers.
They are afterwards extended to the full length by similar means,
GENERAL EXAMPLES OF WELDING. 135
but at a lower temperature, so that the iron is not so much injured
as when thrice heated to the welding point.
The twisted barrels are made out of long ribands of iron wounl
spirally around a mandrel, and welded on their edges by jumping
them upon the ground, or rather on an anvil embedded therein.
The plain stub barrels are ma le in this manner, from iron manu-
factured from a bundle of stub-nails, welded together and drawn
out into ribands, to insure th3 po.^se^sion of a material most thor-
oughly and intimately worke 1. The Damascus barrels are made
from a mixture of stub-nails and clippings of steel in given pro-
portions, paddled together, male into a bloom, and subsequently
passed through all the stag3S of the manufacture of iron already
explained: to obtain an iron that shall be of unequal quality and
hardness, and therefore display different colors and markings when
oxidized or browned.
Other twisted barrels are made in the like manner, except that
the bars to form the ribands are twisted whilst red-hot like ropes,
some to the right, others to the left, and which are sometimes again
laminated together for greater diversity. They are subsequently
again drawn into the ribands and wound upon the mandrel, and
frequently two or three differently-prepared pieces are placed side
by side to form the complex and ornamental figures for the barrels
of fowling-pieces, described as "stub-twist, wire-twist, Damascus-
twist" etc.
A method amongst others of the formation of the Damascus gun-
barrels : By arranging twenty-five thin bars of iron and mild steel
in alternate layers, welding the whole together, drawing it down
small, twisting it like a rope, and again welding three such ropes,
for the formation of the riband, which is then spirally twisted to
form a barrel, that exhibits, when finished and acted upon by acids,
a diversified laminated structure, resembling when properly man-
aged an ostrich feather.
When the illumination by gas was first introduced in the large
way, the old musket-barrels, laid by in quiet retirement from the
fatigues of war, were employed for the conveyance of gas ; and
by a curious coincidence, various iron foundries desisted in a great
measure from the manufacture of iron ordnance, and took up the
peaceful employment of casting pipes for gas and water.
The breech ends of the musket-barrels were broached and tapped,
and the muzzles were screwed externally to connect the two
without detached sockets. From the rapid increase of gas illu-
mination, the old gun-barrels soon became scarce, and new tubes
with detached sockets, made by the old barrel -forgers, were first
resorted to. This led to a series of valuable contrivances for the
manufacture of the wrought-iron tubes, under which the tubes
were first bent up by hand-hammers and swages, to bring the
edges near together ; and they were welded between semi-circular
swages, fixed respectively in the anvil, and the face of a small tilt-
hammer worked by machinery, by a series of blows along the
136 THE PRACTICAL METAL- WORKER'S ASSISTANT.
tube, either with or without a mandrel. The tube was completed
on being passed between rollers with half-round grooves, which
forced it over a conical or egg-shaped piece at the end of a long
bar, to perfect the interior surface.
Various steps of improvement have been since made. For in-
stance, the skelps were bent at two squeezes, first to the bemi-
cylindrical and then to the tubular form (preparatory to welding),
between a swage-tool five feet long worked by machinery. The
whole process was afterwards carried on by rollers, but abandoned
on account of the unequal velocity at which the greatest and least
diameters of the rollers travelled.
In the present method of manufacturing the patent welded tube,
the end of the skelp is bent to the circular form, its entire length
is raised to the welding heat in an appropriate furnace, and as it
leaves the furnace almost at the point of fusion, it is dragged by
the chain of a draw-bench, after the manner of wire, through a
pair of tongs with two bell-mouthed jaws. These are opened at
the moment of introducing the end of a skelp, which is welded
without the agency of a mandrel.
By this ingenious arrangement wrought-iron tubes may be made
from the diameter of six inches internally and about one-eighth to
three-eighths of an inch thick, to as small as one-quarter of an
inch diameter and one-tenth bore ; and so admirably is the joining
effected in those of the best description, that they will withstand
the greatest pressure of gas, steam or water, to which they have
been subjected, and they admit of being bent both in the heated
and cold state almost with impunity. Sometimes the tubes are
made one upon the other when greater thickness is required ; but
these stout pipes, and those larger than three inches, are compara-
tively but little used. The wrought-iron tubes of ^lydrostatic
presses, which measure about half an inch internally, and one-
fourth to three-eighths of an inch thick in the metal, are fre-
quently subjected to a pressure equal to four tons on each square
inch.
Various articles, with large apertures, are made not by punch-
ing or cutting out the holes, but by folding the metal around the
beak iron and finishing them upon a triblet of the appropriate
figure. Thus the complete smithy is generally furnished with a
series of cones turned in the lathe, for making rings, the ends of
which are folded together and welded, such as Fig. 90. The same
rings when made of such cast-steel as does not admit of being
welded, are first punched with a small hole and gradually thinned
out by blows around the margin until they reach the diameter
sought. But this, like numerous other works, requires considera-
ble forethought to proportion the quantity of the material to its
ultimate form and bulk, so that the work may not in the end be-
come either too slight or too heavy.
Chains may be taken as another familiar example of welding.
In these the iron is cut off with a plain chamfer, as from the annu-
GENERAL EXAMPLES OF WELDIXG. 137
lar form of the links their extremities cannot slide asunder when
struck. Every succeeding link is bent, introduced, and finally
welded. In some of these welded chains the links are no more
than half a-n inch long, and the iron wire one-eighth of an inch
diameter. Several inches of such chain are required to weigh 0113
pound. These are made with great dexterity by a man and a boy
at a small fire. The curbed chains are welded in the ordinary form
and twisted afterwards, a few links being made red-hot at a time
for the purpose.
The massive cable-chains are made much in the same manner,
although partly by aid of machinery. The bar of iron, now one,
one and a half, or even two inches in diameter, is heated, and the
scarf is made as a plain chamfer by a cutting machine ; the link is
then formed by inserting the end of the heated bar within a loop
in the edge of an oval disk which may be compared to a chuck
fixed on the end of a lathe mandrel. The disk is put in gear with
the steam-engine; it makes exactly one revolution, and throws
itself out of motion; this bends the heated extremity of the iron
into an oval figure. Afterwards it is detached from the rod with
a chamfered cut by the cutting machine, which at one stroke makes
the second scarf of the detached link, and the first of that next to
be curled up.
The link is now threaded to the extremity of the chain, closed
together, and transferred to the fire, the loose end being carried by
a traverse crane. When the link is at the proper heat, it is re-
turned to the anvil, welded, and dressed off between top and bot-
tom tools, after which the cast-iron transverse stay is inserted, and
the link having been closed upon the stay, the routine is recom-
menced. The work commonly requires three men, and the scarf
is placed at the side of the oval link, and flatway through the
same. In similar chains made by hand it is perhaps more cus-
tomary to weld the link at the crown, or small end.
The tires of wrought-iron wheels for locomotive engines and
carriages, are in general bent to the circle by somewhat analogous
means to those employed in chain-making, as are likewise the
skelps for the twisted barrels of guns. The latter only require a
mandrel or spindle with a winch-handle at the one extremity, and
a loop for the end of the skelp, which is wound in contact with
the mandrel by means of a fixed bar placed near the same. Such
barrels are coiled up in three lengths, which are joined together
after the spirals are welded.
Wheels for railways display many curious examples of smith-
ing ; thus some, except the nave, are made entirely by welding ;
others are partly combined with rivets; in all the nave or boss is a
mass of cast-iron usually poured around the ends of the spokes.
The common practice of welding the tires of railway wheels is
now as follows : the tires are cut off with ridges in the centre, so
as in meeting to form two angular notches, into which two thin
iron wedges are subsequently welded radially ; the four parts thus
J38 THE PRACTICAL METAL-WORKER'S ASSISTANT.
united together in the form of a cross, make a very secure joint
without the necessity for upsetting the iron, which would distort
the form of the tire.
The succeeding illustration of the practice of forging will be that
of the formation of a hatchet, Figs. 91 and 92, which like many
similar tools is made by doubling the iron around a mandrel, to
form the eye of the tool ; it will also permit the description of some
other general proceedings and likewise the introduction of the steel
for the cutting edge.
Figs. 90
94
In making the hatchet, a piece of flat iron is selected of the widtli
of A E, and twice the length of A D ; it is thinned and extended
sideways before it is folded together, to form the projections near
B and F, by blows with the pane of the hammer or a round-edged
fuller, on the lines A B to E F, but the metal must be preserved
of the full thickness at the part A E, to form the poll of the hatchet,
although a piece of steel is frequently welded on at that part as a
previous step. The work is then bent round a mandrel, Figs. 93
and 94, exactly of the section of the eye as seen in Fig. 92, and
the work is welded across the line B F ;• the mandrel is again in-
troduced, and the eye is perfected.
A slip of shear-steel, equal in length to D II, is next inserted be-
tween the two tails of the iron, as yet of their original size, up to
the former weld, and all three are welded together between C, G,
D, H : the combined iron and steel are now drawn out sideways,
by blows of the pane of the hammer on and between C D and G H,
to extend them together to I J. The tool is then flattened and
smoothed with the face of the hammer, and the edges are pared
with straight or circular chisels to the particular pattern, and
trimmed with a round-faced hammer, or a top fuller.
In smoothing off the work, the smith pursues his common
method of first removing with a file the hard black scales that
appear like spots when the work is removed from the fire ; he
then dips the hammer in the slake trough, and lets fall upon the
anvil a few drops of the water it picks up, the explosion of which
when the red-hot metal is struck upon it, makes a smart report
and detaches the scales that would be otherwise indented in the
work. It should be observed that the mandrel, Fig. 93, is pur-
GENERAL EXAMPLES OF WELDING. 139
posely made very taper, and is introduced into the hole from
both sides, so that the eye may be smaller in the middle ; when
therefore the handle of the tool is carefully fitted and wedged in,
the handle is, as it were, dove-tailed, and the tool can neither fly
off nor slip down the handle ; the same mode is also adopted for
the heads of hammers.
In spades, and many similar implements, the steel is introduced
between the two pieces of iron of which the tools are made ; in
others, as plane irons and socket chisels, it is laid on the outside,
and the two are afterwards extended in length or width to the
required size. The ordinary chisel for the smith's shop is made
by inserting the steel in a cleft, as in Fig. 85, and so is also the
pane of a hammer ; but the flat face of the hammer is sometimes
stuck on whilst it continues at the extremity of a flat bar of steel ;
it is then cut off, and the welding is afterwards completed. At
other times the face of the hammer is prepared like a nail, with a
small spike and a very large head, so as to be driven into the
iron to retain its position, until finally secured by the operation of
welding.
In putting a piece of steel into the end of an iron rod to serve
for a centre, the bar is heated, fixed horizontally in the vice, and
punched lengthways with a sharp square punch for the reception of
the steel, which is drawn down like a taper tang or thick nail, and
driven in ; the whole is then returned to the fire, and when at the
proper heat united by welding^the blows being first directed as
for forming, a very obtuse cone, to prevent the piece of steel from
dropping out.
For some few purposes the blistered steel is used for welding,
either to itself or to iron; it is true the first working under the
hammer in a measure changes it to the condition of shear-steel, but
less efficiently so than when the ordinary course of manufacture is
pursued, as the hammering is found to improve steel in a remark-
able and increasing degree.
For the majority of works in which it is necessary to weld steel
to iron, or steel to steel, the shear, or double shear, is exceedingly
suitable; it is used for welding upon various cutting tools, as the
majority of cast-steel will not endure the heat without crumbling
under the hammer. Shear-steel is also used for various kinds of
springs, and for some cutting tools requiring much elasticity.
It is more usual to reserve the cast-steel for those works in which
the process of welding is not required, although of late years mild
cast-steel, or welding cast-steel, containing a smaller proportion of
carbon has been rather extensively used ; but in general the
harder the steel the less easily will it admit of welding, and not
^infrequently it is altogether inadmissible.
The hard or harsh varieties of cast-steel, are somewhat more
manageable when fused borax is used as a defence instead of sand,
either sprinkled on in powder or rubbed on in a lump : and cast-
steel otherwise intractable may be sometimes welded to iron by first
140 THE PRACTICAL METAL-WORKER'S ASSISTANT.
heating the iron pretty smartly, then placing the cold steel beside
it in the fire, and welding them the moment the steel has acquired
its maximum temperature, by which time the iron will be fully up
to the welding heat. When both are put into the fire cold alike,
the steel is often spoiled before the iron is nearly hot enough,
and therefore it is generally usual to heat the iron and steel sepa-
rately, and only to place them in contact towards the conclusion
of the period of getting up the heat. In forging works either of
iron or steel, the uniformity of the hammering tends greatly to
increase and equalize the strength of each material ; and in steel.
judicious and equal forging greatly lessens also the after-risk in
hardening.
When cast-steel has been spoiled by overheating, it may be par-
tially recovered by four or five re.heatings and quenchings in water,
each carried to an extent a little less and less than the first excess ;
and lastly, the steel must have a good hammering at the ordinary
red heat. Some go so far as to prefer for cutting tools the steel
thus recovered, but this seems a most questionable policy, although
the change wrought by this treatment is really remarkable ; as the
fragment broken off from the bar in the spoiled state, and another
from the same bar after part restoration and hardening, will ex-
hibit the extreme characters of coarse and fine.
The hammering I suspect to be the principal requisite, and in
superior tools it should be continued until the work is nearly cold,
to produce the maximum amount of condensation before harden-
ing ; but no hammering will restore the loss of tenacity consequent
upon the over-heating, or even the too frequent heating, of steel,
without excess.
CONCLUDING EEMARKS ON FORGING ; AND THE APPLICATIONS
OF HEADING TOOLS, SWAGE TOOLS, PUNCHES, ETC. — With the
utmost care and unlimited space, it would have been quite impos-
sible to have conveyed the instructions called for, in forging the
thousand varieties of tools, and parts of mechanism the smith is
continually called upon to produce ; and all that could be reason-
ably attempted in this place, was to convey a few of the general
features and practices of this most useful and interesting brancli
of industry. It is hoped, that such combinations of these methods
may be readily arrived at as will serve for the majority of or-
dinary wants.
The smith in all cases selects or prepares that particular form
and magnitude of iron, and also adopts that order of proceeding,
which experience points out as being the most exact, sound, and
economical. In this he is assisted by a large assortment of vari-
ous tools and moulds for such parts of the work as are often re-
peated, or that are of a character sufficiently general to warrant
the outlay, and to some of which I will advert.
The heading tools, Figs. 53 and 54, are made -)f all sizes and
varieties of form ; some with a square recess to produce a square
beneath the head, to prevent the bolt from being turned round in
GENERAL EXAMPLES OF WELDING.
141
the act of tightening its nut ; others for countersunk and round-
headed bolts, with and without
95 • square shoulders : many similar
heading tools are used for all those
parts of work which at all resem-
ble bolts, in having any sudden en-
largement from the stem or shaft.
The holes in the swage block, Fig.
95, are used after the manner of
heading tools for large objects ; the
grooves and recesses around its
margin, also serve in a variety of
works as bottom swages beyond
the size of those fitted to the anvil
At the opposite extreme of the
heading tools, as to size, may be
noticed those constantly employed in producing the smallest kinds
of nails, brads and rivets, of various denominations, some of which
heading tools divide in two parts like a pair of spring forceps to
release the nails after they have been forged.
The forge used by the nail-makers is built as a circular pedestal
with the fire in the centre and the chimney directly over it ; the
rock-staff of the bellows extends entirely around the forge, so that
one of the four or five persons who work at the same fire is con-
tinually blowing it, whence the fire is always at a heat proper for
welding, and which keeps the nails sound and good. These kinds
are called wrought naih and brads, in contradistinction to similar
nails cut out of sheet-iron by various processes of shearing and
punching, which latter kinds are known as cut brads and nails,
and will be adverted to hereafter.
The top and bottom rounding tools, Fig. 50, are made of all
diameters for plain cylindrical works : and when they are used for
objects the different parts of which are of various diameters, it
requires much care to apply them equally on all parts of the work,
that the several circles may be concentric and true one with the
other, or possess one axis in common. To insure this condition
some of these rounding tools are made of various and specific
forms, for the heads of screws, for collars, flanges or enlargements,
which are of continual occurrence in machinery ; for the orna-
mental swells or flanges about the iron work of carriages, and
other works. Such tools, like the pair represented in Figs. 96 and
97, are called swage or collar tools ; they save labor in a most
important degree, and are thus made. A solid mould, core or
striker, exactly a copy of the work to be produced, is made of
steel by hand-forging, and then turned in the lathe to the required
form, as shown in Fig. 98.
The top tool is first moulded to the general form in an appro-
priate aperture in the swage block, Fig. 95, it is faced with steel
like a hammer, and the core, Fig. 98, is indented into it; the blows
142
THE PRACTICAL METAL-WORKERS ASSISTANT.
of the sledge-hammer not being given directly upon the core, but
upon some hollow tool previously made ; otherwise the core must
be filed partly flat to present a plane surface to the hammer. The
bottom tool, which is fitted to the anvil, is made in a similar man
ner, and sometimes the two are finished at the same time whilst
Figs. 96
102
101
not, with the cold striker between them ; their edges are carefully
rounded with a file so as not to cut the work, and lastly they are
hardened, under a stream of water.
In preparing the work for the collar tools, when the projection
is inconsiderable, the work is always drawn down rudely to the
form between the top and bottom fullers, as in Fig. 48 ; but for
greater economy, large works in iron are sometimes made by fold-
ing a ring around them as in Fig. 56. The metal for a large ring
is occasionally moulded in a bottom tool, like Fig. 99, and coiled
up to the shape of Fig. 100, after which it is closed upon the central
rod between the swages, and then welded within them. The tools
are slightly greased, to prevent the work from hanging to them,
and from the same motive their surfaces are not made quite flat or
perpendicular, but slightly conical, and all the angles are obliterated
and rounded.
The spring swage tool, represented in Fig. 101, is used for some
small manufacturing purposes ; it differs in no respect from the
former, except in the steel spring which connects the two parts; it
is employed for light single hand-forgings. Other workmen use
swage tools, such as Fig. 102, in which there is a square recess in
the bottom tool to fit the margin of the top-tool so as to guide it
exactly to its true position. In practice the recess in the bottom
tool would be deeper, and taper or larger above to guide the tool
more easily to its place ; but if so drawn the figure would have
been less distinct. This kind also may be used for single hand
works, and is particularly suited to those which are of rectangular
section, as the shoulders of table-knives ; these do not admit of
being twisted round, which movement furnishes the guide for the
position of the top-tool in forging circular works.
GENERAL EXAMPLES OF WELDING.
143
The smith has likewise a variety of punches of all shapes and
sizes, for making holes of corresponding forms ; and also drifts or
mandrels, used alone for finishing them, many of which, like the
turned cones, are made from a small to a large size to serve for
objects of various sizes. Two examples of the very dexterous use
of punches, are in the hands of almost every person, namely ordi-
nary scissors and pliers.
The first are made from a small bar of flat steel ; the end is flat-
Figs. 104
105
tened and punched with a small round hole, which is gradually
opened upon a beak-iron, Fig. 103, attached to the square hole of the
anvil ; the beak-iron has a shallow groove (accidentally omitted)
for rounding the inside of the bows. The remaining parts of the
scissors are moulded jointly by the hammer, and bottom swage
tools ; but the bows are mostly finished by the eye alone.
In some pliers, the central half of the joint is first made ; the
aperture in the other part is then punched through sideways, and
Figs. 106
107
sufficiently bulged out to allow the middle joint to be passed
through, after which the outsides are closed upon the centre. This
proceeding exhibits, in the smallest kinds especially a surprising
degree of dexterity and dispatch, only to be arrive 1 at by very
great practice; and which in this and numerous other instances of'
manufacture could be scarcely attained but for the enormous de-
THE PRACTICAL
mand, which enables a great subdivision of labor to be success-
fully applied to their production.
Figs. 104, 105, 106 and 107 represent the ordinary trip and tilt
hammer used in this country. The drawings are taken from those
manufactured at the Lowell Machine Shop, Lowell, Mass., of which
W. A. Burke is the superintendent. The smaller trip-hammers
are mounted with iron bed-pieces firmly bolted on large timber,
furnished with a cast-iron stake, adapted to drawing and swaging
spindles, bolts, and other small work, balance wheels on cam-shaft,
and a husk adjustable by bolts and screws; the hammer-head
weighing from thirty to one hundred and twenty-five pounds,
driven by a belt. The heavy trip-hammer, manufactured in this
shop, has a very heavy strong cast-iron frame, adjustable husk,
cast-iron stake, driven by belt with balance-wheel on cam-shaft,
and suited to a hammer-head weighing from one hundred and
twenty-five to four hundred pounds.
CHAPTER IX.
HARDENING AND TEMPERING.
GENERAL VIEW OF THE SUBJECT. — When the malleable metals
fire hammered or rolled, they generally increase in hardness, in
elasticity, and in density or specific gravity; which effects are pro-
duced simply from the closer approximation of their particles, and
in this respect steel may be perhaps considered to excel, as the
process called hammer-hardening, which simply means hammer-
ing without heat, is frequently employed as the sole means of har-
dening some kinds of steel springs, and for which it answers re-
markably well.
After a certain degree of compression, the malleable metals
assume their closest and most condensed states ; and it then be-
comes necessary to discontinue the compression or elongation, as
it would cause the disunion or cracking of the sheet or wire, or
else the metal must be softened by the process of annealing.
The metals, lead, tin, and zinc, are by some considered to be
perceptibly softened by immersion in boiling water : but such of
the metals as will bear it are generally heated to redness, the co
hesion of the mass is for the time reduced, and the metal becomes
as soft as at first, and the working and annealing may be thus
alternately pursued, until the sheet metal, or the wire, reaches its
limit of tenuity.
The generality of the metals and alloys suffer no very observ-
able change, whether or not they are suddenly quenched in water
HARDENING AND TEMPERING. 145
from the red heat. Pure hammered iron, like the rest, appears
after annealing, to be equally soft whether suddenly or slowly
cooled ; some of the impure kinds of malleable iron harden by im-
mersion, but only to an extent that is rather hurtful than useful,
and which may be considered as an accidental quality.
Steel however receives by sudden cooling that extreme degree
of hardness combined with tenacity, which places it so incalculably
beyond every other material for the manufacture of cutting tools ;
especially as it likewise admits of a regular gradation from extreme
hardness to its softest state, when subsequently re-heated or tempered.
Steel therefore assumes a place in the economy of manufacture un-
approachable by any other material: consequently we may safely
say that without it, it would be impossible to produce nearly all
our finished works in metal and other hard substances ; for although
some of the metallic alloys are remarkable for hardness, and were
used for various implements of peaceful industry, and also those of
war, before the invention of steel, yet in point of absolute and
enduring hardness, and equally so in respect to elasticity and ten-
acity, they fall exceedingly short of hardened steel.
Hammer hardening renders the steel more fibrous and less crys-
talline, and reduces it in bulk; on the other hand, fire hardening
makes steel more crystalline, and frequently of greater bulk ; but
the elastic nature of hammer hardened steel will not take so wide
nor so efficient a range as that which is fire hardened.
If we attempt to seek the remarkable difference between pure
iron and steel in their chemical analyses, it appears to result from
a minute portion of carbon; and cast-iron, which possesses a much
larger share, presents, as we should expect, somewhat, similar
phenomena.
Iron semi-steelified ^ contains one 150th of carbon.
Soft cast-steel capable of welding . . .
Cast-steel for common purposes
Cast-steel requiring more hardness . . .
Steel capable of standing a few blows, but quite
unfit for drawing
First approach to a steely granulated fracture
White cast-iron .......
Mottled cast-iron ......
Carbonated cast-iron . . . . . .
Super-carbonated crude iron ....
120th
100th "
90th "
50th "
30th to 40th.
25th
20th
15th
12th "
For the mode of analysis for ascertaining the quantity of carbon
in cast-iron and steel, invented by M. V. Kegnault, Mining Engi-
neer, see Annales de Chimie et de Physique, for January, 1839 ; also
Journal of the Franklin Institute, vol. xxv. p. 327. It is stated
that the analysis is very easy and exact, and may be completed in
half an hour.
Moreover, as the hard and soft conditions of steel may be re-
versed backwards and forwards without any rapid chemical change
in its substance, it has been pronounced to result from internal
10
146 THE PRACTICAL METAL-WORKER'S ASSISTANT.
arrangement or crystallization, which may be in a degree illustrated
and explained by similar changes observed in glass.
A wine-glass, or other object recently blown, and plunged whilst
red hot into cold water, cracks in a thousand places, and even
cooled in warm air it is very brittle, and will scarcely endure the
slightest violence or sudden change of temperature ; and visitors
to the glass-house are often shown that a wine-glass, or other article
of irregular form, breaks in cooling in the open air from its un-
equal contraction at different parts. But the objects would have
become useful, and less disposed to fracture, if they had been
allowed to arrange their particles gradually during their very slow
passage through the long annealing oven or leer of the glass-house,
the end at which they enter being at the red heat, and the opposite
extremity almost cold.
To perfect the annealing, it is not unusual with lamp-glasses,
tubes for steam-gages, and similar pieces exposed to sudden transi-
tions of heat and cold, to place them in a vessel of cold water,
which is slowly raised to the boiling temperature, kept for some
hours at that heat and then allowed to cool very slowly : the effect
thus produced is far from chimerical. For such pieces of flint
glass intended for cutting, as are found to be insufficiently an-
nealed, the boiling is sometimes preferred to a second passage
through the leer : lamp-glasses are also much less exposed to frac-
ture when they have been once used, as the heat, if not too sud-
denly applied or checked, completes the annealing.
Steel in like manner when suddenly cooled is disposed to crack
in pieces, which is a constant source of anxiety ; the danger in-
creases with the thickness in the same way as with glass, and the
more especially when the works are unequally thick and thin.
Another ground of analogy between glass and steel appears to
exist in the pieces of unannealed glass used for exhibiting the phe-
nomena formerly called double refraction, but now polarization
of light ; an effect distinctly traced to its peculiar crystalline
structure.
In glass it is supposed to arise from the cooling of the external
crust more rapidly than the internal mass ; the outer crust is there-
fore in a state of tension, or restraint, from an attempt to squeeze
the inner mass into a smaller space than it seems to require ; and
from the hasty arrangement of the unannealed glass the natural
positions of its crystals are in a measure disturbed or dislocated.
It has been shown experimentally, that a re- arrangement of the
particles of glass occurs in the process of annealing, as, of two
pieces of the same tube each 40 inches long, the one' sent through
the leer contracted one-sixteenth of an inch more than the other,
which was cooled as usual in the open air. Tubes for philosophi-
cal purposes are not annealed, as their inner surfaces are apt to
become soiled with the sulphur of the fuel ; they are in conse-
quence very brittle and liable to accident.
The unannealed glass, when cautiously heated and slowly cooled,
HARDENING AND TEMPERING. 147
ceases to present the polarizing effect, and the steel similarly
treated ceases to be hard ; and may we not therefore indulge in the
speculation, that in both cases a peculiar crystalline structure is
consequent upon the unannealed or hardened state ?
In the process of hardening steel, water is by no means essen-
tial, as the sole object is to extract its heat rapidly, and the follow-
ing are examples, commencing with the condition of extreme
hardness, and ending with the reverse condition.
A thin heated blade placed between the cold hammer and anvil,
or other good conductors of heat, becomes perfectly hard. Thicker
pieces of steel, cooled by exposure to the air upon the anvil, be-
come rather hard, but readily admit of being filed. They become
softer when placed on cold cinders, or other bad conductors of
heat. Still more soft when placed in hot cinders, or within the
fire itself, and cooled by their gradual extinction. When the steel
is encased in close boxes with charcoal powder, and it is raised to
a red-heat and allowed to cool in the fire or furnace, it assumes its
softest state ; unless, lastly, we proceed to its partial decomposition.
This is done by enclosing the steel with iron turnings or filings,
the scales 'from the smith's anvil, lime, or other matters that will
abstract the carbon from its surface ; by this mode it is super-
ficially decarbonized, or reduced to the condition of pure soft iron,
in the manner practised by Mr. Jacob Perkins, of Massachusetts,
in his most ingenious and effective combination of processes,
employed for producing in unlimited numbers absolutely identi-
cal impressions of bank notes and checks, for the prevention of
forgery. These methods of treating steel will be hereafter noticed.
A nearly similar variety of conditions might be referred to as
existing in cast-iron in its ordinary state, governed by the magni-
tude, quality, and management of the castings ; independently of
which, by one particular method, some cast-iron .may be rendered
externally as hard as the hardest steel ; such are called chilled iron
castings ; and, as the opposite extreme, by a method of annealing
combined with partial decomposition, malleable iron costings may
be obtained, so that cast-iron nails may be clenched.
Again, the purest iron, and most varieties of cast-iron, may, by
another proceeding, be superficially converted into steel, and then
hardened, the operation being appropriately named case-hardening.
I therefore propose to illustrate these phenomena collectively, under
three divisions : first, the hardening and tempering of steel ;
secondly, the hardening and annealing of cast-iron ; and thirdly,
the process of case-hardening.
PRACTICE OF HARDENING AND TEMPERING STEEL. — It may per-
haps be truly said, that upon no one subject connected with me-
chanical art does there exist such a contrariety of opinion, not
unmixed with prejudice, as upon that of hardening and tempering
steel ; which makes it often difficult to reconcile the practices fol-
lowed by different individuals in order to arrive at exactly similar
ends. The real difficulty of the subject occurs in part from the
148 THE PRACTICAL METAL-WORKER'S ASSISTANT.
mysteriousness of the change ; and from the absence of defined
measures, by which either the steps of the process itself, or the
value of the results when obtained, may be satisfactorily measured ;
as each is determined almost alone by the ^unassisted senses of
sight and touch, instead of by those physical means by which
numerous other matters may be strictly tested and measured,
nearly without reference to the judgment of the individual, which
in its very nature is less to be relied upon.
The excellence of cutting-tools, for instance, is pronounced upon
their relative degrees of endurance, but many accidental circum-
stances here interfere to vitiate the strict comparison : and in respect
to the measure of simple hardness, nearly the only test is the resist-
ance the objects offer to the file, a mode in two ways defective, as
the files differ amongst themselves in hardness ; and they only serve
to indicate in an imperfect manner to the touch of the individual, a
general notion without any distinct measure, so that when the opinion
of half a dozen persons may be taken, upon as many pieces of steel
differing but slightly in hardness, the want of uniformity in their
decisions will show the vague nature of the proof.-
Under these circumstances, instead of recommending any partic-
ular methods, I have determined to advance a variety of practical
examples derived from various sources, which will serve in most
cases to confirm, but in some to confute one another ; leaving to
every individual to follow those examples which may be the most
nearly parallel with his own wants. There are, however, some few
points upon which it may be said that all are agreed ; namely,
The temperature suitable to forging and hardening steel differs
in some degree with its quality and its mode of manufacture ; the
heat that is required diminishes with the increase of carbon :
In every case the lowest available temperature should be employed
in each process, the hammering should be applied in the most equal
manner throughout, and for cutting tools it should be continued until
they are nearly cold :
Coke or charcoal is much better as a fuel than fresh coal, the
sulphur of which is highly injurious :
The scale should be removed from the face of the work to expose
it the more uniformly to the effect of the cooling medium :
Hardening a second time without the intervention of hammering
is attended with increased risk ; and the less frequently steel passes
through the fire the better.
In hardening and tempering steel there are three things to be
considered ; namely, the means of heating the objects to redness,
the means of cooling the same, and the means of applying the heat
for tempering or letting them down. I will speak of these, sepa-
rately, before giving examples of their application.
The smallest works are heated with the flame of the blowpipe,
and are occasionally supported upon charcoal ; but as the blowpipe
is used to a far greater extent in soldering, its management will be
described in the chapter devoted to that process.
HARDENING AND TEMPERING.
For objects that are too large to be heated by the blowpipe, and
too small to be conveniently warmed in the naked fire, various pro-
tective means are employed. Thus, an iron tube or sheet-iron box
inserted in the midst of the ignited fuel is a safe and cleanly way ;
it resembles the muffle employed in chemical works. The work is
then managed with long forceps made of steel or iron wire, bent in
the form of the letter U, and flattened or hollowed at the ends. A
crucible or an iron pot about four to six inches deep, filled with
lead and heated to redness, is likewise excellent, but more particu-
larly for long and thin tools, such as gravers for artists, and other
slight instruments ; several of these may be inserted at once,
although towards the last they should be moved about to equalize
the heat ; the weight of the lead makes it desirable to use a bridle
or trevet for the support of the crucible. Some workmen place on
the fire a pan of charcoal dust, and heat it to redness.
Great numbers of tools, both of medium and large size, are heated
in the ordinary forge fire, which should consist of cinders rather
than fresh coals ; coke and also charcoal are used, but far less gen-
erally ; recourse is also had to hollow fires, the construction of
which was explained at page 94 ; but the bellows should be very
sparingly used, except in blowing up the fire before the introduc-
tion of the work, which should be allowed ample time to get hot, or,
as it is called, to " soak"
"Which method soever may be resorted to for heating the work,
the greatest care should be given to communicate to all the parts
requiring to be hardened a uniform temperature, and which is only
to be arrived at by cautiously moving the work to and fro to expose
all parts alike to the fire ; the difficulty of accomplishing this of
course increases with long objects, for which fires of proportionate
length are required.
It is far better to err on the side of deficiency than of excess of
heat ; the point is rather critical, and not alike in all varieties of
steel. Until the quality of the steel is familiarly known, it is a safe
precaution to commence rather too low than otherwise, as then the
extent of the mischief will be the necessity for a repetition of the
process at a higher degree of heat; but the steel, if burned or
over-heated, will be covered with scales, and what is far worse, its
quality will be permanently injured; a good hammering will, in
a degree, restore it ; but this in finished works is generally imprac-
ticable.
Less than a certain heat fails to produce hardness, and in the
opinion of some workmen has quite the opposite effect, and they
consequently resort to it as the means of rapid annealing ; not,
however, by plunging the steel into the water and allowing it to
remain until cold, but dipping it quickly, holding it in the steam
for a few moments, dipping it again and so on, reducing it to the
cold state in a hasty but intermittent manner.
There is another opinion prevalent amongst workmen, that steel
which is "pinny" or as if composed of a bundle of hard wires, is
150 THE PRACTICAL METAL-WORKER'-S ASSISTANT.
rendered uniform in its substance if it is first hardened and then
annealed.
Secondly, the choice of the cooling medium has reference mainly
to the relative powers of conducting heat they severally possess :
the following have been at different times resorted to with various
degrees of success : currents of cold air ; immersion in water in
various states, in oil or wax, and in freezing mixtures ; mercury,
and flat metallic surfaces have been also used. Plain water, at a
temperature of 40° Fahrenheit, has been recommended. On the
whole, however, there appears to be an opinion that mercury gives
the greatest degree of hardness ; then cold salt and water, or water
mixed with various " astringent and acidifying matters ;" plain
water follows ; and lastly, oily mixtures.
I find but one person who has commonly used the mercury.
Many presume upon the good conducting power of the metal,
and the non-formation of steam, which causes a separation betwixt
the steel and water, when the latter is employed as the cooling me-
dium. I have failed to learn the reason of the advantage of salt
and water, unless the fluid have, as well as a greater density, a
superior conducting power. The file-makers medicate the water
in other ways, but this is one of the questionable mysteries which
is never divulged, — although it is supposed that a small quantity
of white arsenic is generally added to water saturated with salt.
One thing, however, may be noticed, that articles hardened in salt
and water are apt to rust, unless they are laid for a time in lime-
water, or some neutralizing agent.
With plain water, an opinion very largely exists in favor of that
which has been used over and over again, even for years, provided
it is not greasy : and when the steel is very harsh, the chill is
taken off plain water to lessen the risk of cracking it. Oily mix-
tures impart to thin articles, such as springs, a sufficient and milder
degree of hardness, with less danger of cracking, than from water ;
and in some cases a medium course is pursued by covering the
water with a thick film of oil, which is said to be adopted occa-
sionally with scythes, reaping-hooks, and thin edge-tools.
A so-called natural spring is made by a vessel with a true and a
false-bottom, the latter perforated with small holes ; it is filled with
water, and a copious supply is admitted beneath the partition ; it
ascends through the holes, and pursues the same current as the
heated portions, which also escape at the top. This was invented
by the late John Oldham, of Dublin, Engineer to the Bank of
England, and was used by him in hardening the rollers for trans-
ferring the impressions to the steel -plates for bank-notes.
Sometimes when neighboring parts of works are required to be
respectively hard and soft, metal tubes or collars are fitted tight
upon the work, to protect the parts to be kept soft from the direct
action of the water, at any rate for so long a period as they retain
the temperature suitable to hardening.
The process of hardening is generally one of anxiety, as the
,
HARDENING AND TEMPERING.. 151
V4f: S/>
sudden transition from heat to cold often causes the works to be4 ' '
come greatly distorted if not cracked. The last accident is much
the most likely to occur with thick massive pieces, which are, as ft *
were, hardened in layers, — as although the external crust or shell ' •
may be perfectly hard, there is almost a certainty that towards the
centre the parts are gradually less hard ; and when broken, the
inner portions will sometimes admit of being readily filed.
When in the fire the steel becomes altogether expanded, and in
the water its outer crust is suddenly arrested, but with a tendency
to contract from the loss of heat, which cannot so rapidly occur at
the central part ; it may be therefore presumed that the inner bulk
continues to contract after the outer crust is fixed, and which tends
co tear the two asunder, the more especially if there be any de-
fective part in the steel itself. An external flake of greater or
less extent not unfrequently shells off in hardening ; and it often
happens that works remain unbroken for hours after removal from
the water, but eventually give way and crack with a loud report,
from the rigid unequal tension produced by the violence of the
process of hardening.
The contiguity of thick and thin parts is also highly dangerous,
as they can neither receive nor yield up heat in the same times.
The mischief is sometimes lessened by binding pieces of metal
around the thin parts with wire, to save them from the action of
the cooling medium. Sharp angular notches are also fertile sources
of mischief, and where practicable they should be rejected in favor
of curved lines.
As regards both cracks and distortions, it may perhaps be
generally said that their avoidance depends principally upon ma-
nipulation, or the successful management of every step : first, the
original manufacture of the steel, its being forged and wrought so
that it may be equally condensed on all sides with the hammer,
otherwise when the cohesion of the mass is lessened from its be-
coming red hot, it recovers in part from any unequal state of den-
sity in which it may have been placed.
Whilst red hot it is also in its weakest condition. It is there-
fore prone to injury, either from incautious handling with the
tongs, or from meeting the sudden cooling action irregularly, and
therefore it is generally best to plunge works vertically, as all parts
are then exposed to equal circumstances, and less disturbance is
risked than when the objects are immersed obliquely or sideways
into the water, — although for swords, and objects of similar form,
it is found the best to dip them exactly as in making a vertical
downward cut with a sabre, which for this weapon is its strongest
direction.
Occasionally objects are clamped between stubborn pieces of
metal, as soft iron or copper, during their passage through the fire
and water. Such plans can be seldom adopted, and are rarely fol-
lowed, the success of the process being mostly allowed to depend
exclusively upon good general management.
152
THE PRACTICAL METAL-WORKER'S ASSISTANT.
In making the magnets for needles ten inches long, one-fourth
of an inch wide, and the two-hundredth part of an inch thick this
precaution entirely failed; and the needles assumed all sorts of
distortions when released from between the stiff bars within which
they were hardened. The plan was eventually abandoned and the
magnets were heated in the ordinary way within an iron tube, and
were set straight with the hammer after being let down to a
deep orange or brown color. Steel, however, is in the best con-
dition for the formation of good permanent magnets when per-
fectly hard.
In all cases the thick unequal scale left from the forge should be
ground off before hardening, in order to expose a clean metallic
surface, otherwise the cooling medium cannot produce its due and
equal effect throughout the instrument. The edges also should be
left thick, that they may not be burned in the fire; thus it will
frequently happen that the extreme end or edge of a tool is in-
ferior in quality to the part within, and that the instrument is
much better after it has been a few times ground.
Thirdly, the heat for tempering or letting down. Between the
extreme conditions of hard and soft steel there are many interme-
diate grades, the common index for which is the oxidation of the
brightened surface, and it is quite sufficient for practice. These tints,
and their respective approximate temperatures, are thus tabulated :
1. Very pale straw yellow
2. A shade of darker yellow
3. Darker straw yellow .
4. Still darker straw yellow
5. A brown yellow .
6. A yellow, tinged slightly wi
7. Light purple
8. Dark purple .
9. Dark blue . .
h pu
430 de
450
470
490
500
rple 520
530
550
570
590
610
een 630
10. Paler blue ....
11. Still paler blue .
12. Still paler blue, with a tinge of gr
Tools for metals.
| Tools for wood, and screw
) taps, etc.
} Hatchets chipping chisels,
£ and other percussive
) tools, saws, etc.
| Springs.
"Too soft for the above pur-
poses.
The first tint arrives at about 430° F., but it is only seen by
comparison with a piece of steel not heated : the tempering colors
differ slightly with the various qualities of steel.
The heat for tempering being moderate, it is often supplied by
the part of the tool not requiring to be hardened, and which is
not therefore cooled in the water. The workman first hastily tries
with a file whether the work is hard ; he then partially brightens
it at a few parts with a piece of grindstone or an emery stick, that
he maybe enabled to watch for the required color; which attained,
the work is usually cooled in any convenient manner, lest the
body of the tool should continue to supply heat. But when, on the
contrary, the color does not otherwise appear, partial recurrence
is had to the mode in which the work is heated, as the flame
of the candle, or the surface of the clear fire applied, if possible, a
HARDENING AND TEMPERING. 153
little below the part where the color is to be observed, that it may
not be soiled by the smoke.
A very convenient and general manner of tempering small ob-
jects is to heat to redness a few inches of the end of a flat bar of
iron about two feet long ; it is laid across the anvil, or fixed by its
cold extremity in the vice ; and the work is placed on that part of
its surface which is found by trial to be of the suitable tempera-
ture, by gradually sliding the work towards the heated extremity.
In this manner many tools may be tempered at once, those at the
hot part being pushed off into a vessel of water or oil, as they
severally show the required color, but it requires dexterity and
quickness in thus managing many pieces.
Vessels containing oil or fusible alloys carefully heated to the
required temperatures have also been used, and I shall have to
describe a method called "blazing-off" resorted to for many articles,
such as springs and saws, by heating them over the naked fire until
the oil, wax, or composition in which they have been hardened
ignites; this can only occur when they respectively reach their
boiling temperatures and are also evaporated in the gaseous form.
The period of letting down the works is also commonly chosen
for correcting, by means of the hammer, those distortions which so
commonly occur in hardening ; this is done upon the anvil, either
with the thin pane of an ordinary hammer, or else with a hack-
hammer, a tool terminating at each end in an obtuse chisel edge
which requires continual repair on the grindstone.
The blows are given on the hollow side of the work, and at right
angles to the length of the curve; they elongate the concave side,
and gradually restore it to a plane surface, when the blows are dis-
tributed consistently with the position of the erroneous parts.
The hack-hammer unavoidably injures the surface of the work,
but the blows should not be too violent, as they are then also more
prone to break the work, the liability to which is materially
lessened when it is kept at or near the tempering heat, and the
edge o%f the hack-hammer is slightly rounded.
COMMON EXAMPLES OF HARDENING AND TEMPERING STEEL. —
Watchmakers' drills of the smallest kinds are heated in the blue
part of the flame of the candle ; larger drills are heated with the
blowpipe flame, applied very obliquely, and a little below the
point ; when very thin they may be whisked in the air to cool
them, but they are more generally thrust into the tallow of the
candle or the oil of a lamp ; they are tempered either by their own
heat, or by immersion in the flame below the point of the tool.
For tools between those suited to the action of the blowpipe
and those proper for the open fire, there are many which require
either the iron tube, or the bath of lead or charcoal described at
page 149, but the greater number of works are hardened in the
ordinary smith's fire, without such defences.
Tools of moderate size, such as the majority of turning tools,
carpenters' chisels, and gouges, and so forth, are generally heated
154 THE PRACTICAL METAL-WORKER'S ASSISTANT.
in the open fire ; they require to be continually drawn backward*
and forwards through the fire, to equalize the temperature applied,
they are plunged vertically into the water, and then moved about
sideways to expose them to the cooler portions of the fluid. If
needful, they are only dipped to a certain depth, the remainder
being left soft.
Some persons use a shallow vessel filled only to the height of
the portion to be hardened, and plunge the tools to the bottom ;
but this strict line of demarkation is sometimes dangerous, as the
tools are apt to become cracked at the part, and therefore a small
vertical movement is also generally given, that the transition from
the hard to the soft part may occupy more length.
Kazors and penknives are too frequently hardened without the
removal of the scale arising from the forging ; this practice, which is
not done with the lest works, cannot be too much deprecated. The
blades are heated in a coke or charcoal fire, and dipped into the
water obliquely. In tempering razors, they are laid on their
backs upon a clear fire, about half-a-dozen together, and they are
removed one at a time, when the edges, which are as yet thick,
come down to a pale straw color. Should the backs accidentally
get heated beyond the straw color, the blades are cooled in water,
but not otherwise. Penknife blades are tempered, a dozen or two
at a time, on a plate of iron or copper about twelve inches long,
three or four wide, and about a quarter of an inch thick ; the blades
are arranged close together on their backs, and lean at an angle
against each other. As they come down to the temper, they are
picked out with small pliers and thrown into water if necessary ;
other blades are then thrust forward from the cooler parts of the
plate to take their place.
Hatchets, adzes, cold chisels, and numbers of similar tools, in
which the total bulk is considerable compared with the part to be
hardened, are only partially dipped ; they are afterwards let down
by the heat of the remainder of the tool, and when the color indic-
ative of the temper is attained, they are entirely quenched. * With
the view of removing the loose scales, or the oxidation acquired in.
the fire, some workmen rub the objects hastily in dry salt before
plunging them, in the water, in order to give them a cleaner and
whiter face.
In hardening large dies, anvils, and other pieces of considerable
size, by direct immersion, the rapid formation of steam at the sides
of the metal prevents the free access of the water for the removal
of the heat with the required expedition ; in these cases, a copious
stream of water from a reservoir above is allowed to fall on the
surface to be hardened. This contrivance is frequently called a
" float," and although the derivation of the name is not very clear,
the practice is excellent, as it supplies an abundance of cold water ;
and which, as it falls directly on the centre of the anvil, is sure to
render that part hard. It is, however, rather dangerous to stand
near such works at the time, as when the anvil face is not perfectly
HARDENING AND TEMPERING. 155
welded, it sometimes in part flies off with great violence and a loud
report. •
Occasionally the object is partly immersed in a tank beneath the
fall of water, by means of a crane and slings ; it is ultimately tem-
pered with its own heat, and dropped in the water to become en-
tirely cold.
Oil, or various mixtures of oil, tallow, wax, and resin, are used
for many thin and elastic objects, such as needles, fish-hooks, steel
pens and springs, which require a milder degree of hardness than
is given by water.
For example, steel pens are heated in large quantities in iron
trays within a furnace, and are then hardened in an oily mixture ;
generally they are likewise tempered in oil, or a composition the
boiling point of which is the same as the temperature suited to
letting them down. This mode is particularly expeditious, as the
temper cannot fall below the assigned degree. The dry heat of an
oven is also used, and both the oil and oven may be made to serve
for tempers harder than that given by boiling oil ; but more care
and observation are required for these lower temperatures.
Saws and springs are generally hardened in various composi-
tions of oil, suet, wax and other ingredients, which, however, lose
their hardening property after a few weeks' constant use : the saws
are heated* in long furnaces, and then immersed horizontally and
edge-ways in a long trough containing the composition ; two troughs
are commonly used, the one until it gets too warm, then the other
for a period, and so on alternately. Part of the composition is
wiped off the saws with a piece of leather, when they are removed
from the trough, and they are heated one by one over a clear coke
lire, until the grease inflames ; this is called " blazing o/f."
The composition used by an experienced saw-maker is two
pounds of suet and a quarter of a pound of bees-wax to every
gallon of whale-oil ; these are boiled together, and will serve for
thin works and most kinds of steel. The addition of black resin,
to the extent of about one pound to the gallon, makes it serve for
thicker pieces and for those it refused to harden before ; but the
resin should be added with judgment, or the works will become
too hard and brittle. The composition is useless when it has been
constantly employed for about a month ; the period depends, how-
ever, on the extent to which it is used, and the trough should be
thoroughly cleansed out before new mixture is placed in it.
The following recipe is recommended :
Twenty gallons of spermaceti oil ;
Twenty pounds of beef suet rendered ;
One gallon of neat's-foot oil ;
One pound of pitch ;
Three pounds of black resin.
These last two articles must be previously melted together, aiid
then added to the other ingredients; when the whole must be
heated in a proper iron vessel, with a close cover fitted to it, until
156 THE PRACTICAL METAL-WORKERS ASSISTANT.
the moisture is entirely evaporated, and the composition will take
fire on a flaming body being presented to its surface, but which
must be instantly extinguished again by putting on the cover of
the vessel.
When the saws are wanted to be rather hard, but little of the
grease is burned off; when milder, a larger portion; and for a
spring temper, the whole is allowed to burn away. When the
work is thick, or irregularly thick and thin, as in some springs, a
second and third dose is burned off, to insure equality of temper
at all parts alike.
Gun-lock springs are sometimes literally fried in oil for a con-
siderable time over a fire in an iron tray ; the thick parts are then
sure to be sufficiently reduced, and the thin parts do not become
the more softened from the continuance of the blazing heat.
Springs and saws appear to lose their elasticity, after hardening
and tempering, from the reduction and friction they undergo in
grinding and polishing. Towards the conclusion of the manufac-
ture, the elasticity of the saw is jestored principally by hammer-
ing, and partly by heating it over a clear coke fire to a straw
color: the tint is removed by very diluted muriatic acid, after
which the saws are well washed in plain water and dried.
Watch springs are hammered out of round steel wire, of suitable
diameter, until they fill the gage for width, which at the "same time
insures equality of thickness ; the holes are punched in their
extremities, and they are trimmed on the edge with a smooth file ;
the springs are then tied up with binding-wire, in a loose open
coil, and heated over a charcoal fire upon a perforated revolving
plate, they are hardened in oil, and blazed off.
The spring is now distended in a long metal frame, similar to
that used for a saw blade, and ground and polished with emery and
oil, between lead blocks ; by this time its elasticity appears quite
lost, and it may be bent in any direction ; its elasticity is, how-
ever, entirely restored by a subsequent hammering on a very bright
anvil, which "puts the nature into the spring"
The coloring is done over a flat plate of iron, or hood, undei
which a little spirit-lamp is kept burning ; the spring is continually
drawn backwards and forwards, about two or three inches at a
time, until it assumes the orange or deep blue tint, throughout, ac-
cording to the taste of the purchaser ; by many the coloring is
considered to be a matter of ornament, and not essential. The
last process is to coil the spring into the spiral form, that it may
enter the barrel in which it is to be contained ; this is done by a
tool with a small axis and winch handle, and does not require heat.
The balance-springs of marine chronometers, which are in the
form of a screw, are wound into the square thread of a screw of
the appropriate diameter and coarseness ; the two ends of the
spring are retained by side screws, and the whole is carefully en-
veloped in platinum-foil, and tightly bound with wire. The mass
is next heated in a piece of gun barrel closed at the one end, and
HAKDENING AND TEMPERING. 157
plunged into oil, which hardens the spring- almost without discol
oring it, owing to the exclusion of the air by the close platinum
covering, which is now removed, and the spring is let down to the
blue, before removal from the screwed block.
The balance or hair-springs of common watches are frequently
left soft ; those of the best watches are hardened in the coil upon
a plain cylinder, and are then curled into the spiral form between
the edge of a blunt knife and the thumb, the same as in curling up
a narrow ribbon of paper, or the filaments of an ostrich feather.
Thirty -two hundred balance springs weigh about an ounce. The
soft springs are worth 60 cents each ; the hardened and tempered
springs, $1.26 each. This raises the value of the steel, originally
less than four cents, to $2000 and $8000 respectively. But springs
also include the heaviest examples of hardened steel works uncom-
bined with iron : for example, bow-springs for all kind of vehicles,
some intended for railway use, measure 3J feet long, and weigh 50
pounds each piece ; two of these are used in combination ; other
single springs are 6 feet long, and weigh seventy pounds. The
principle of these bow-springs will be immediately seen, by con-
ceiving the common archery bow fixed horizontally with its cord
upwards ; the body of the carriage being attached to the cord
sways both perpendicularly and sideways with perfect freedom.
In hardening them they are heated by being drawn backwards
and forwards through an ordinary forge fire, built hollow, and they
are immersed in a trough of plain water : in tempering them they
are heated until the black red is just visible at night; by daylight
the heat is denoted by its making a piece of wood sparkle when
rubbed on the spring, which is then allowed to cool in the air. The
metal is nine- sixteenths of an inch thick, and some consider five-
eighths the limits to which steel will harden properly, that is suffi-
ciently alike to serve as a spring ; their elasticity is tested far
beyond their intended range.
Great diversity of opinion exists respecting the cause of elastic-
ity in springs ; by some it is referred to different states of elec-
tricity ; by others the elasticity is considered to reside in the thin
blue, oxidized surface, the removal of which is thought to destroy
the elasticity, much in the same manner that the elasticity of a
cane is greatly lost by stripping off its silicious rind. The elastic-
ity of a thick spring is certainly much impaired by grinding off
a small quantity of its exterior metal, which is harder than the
inner portion ; and perhaps thin springs sustain in the polishing a
proportional loss, which is to them equally fatal.
It has been stated that the bare removal of the blue tint from a
pendulum spring, by its immersion in weak acid, caused the
chronometer to lose nearly one minute each hour ; a second and
equal immersion scarcely caused any further loss. It is supposed
springs get stronger, in a minute degree, during the first two or
three years they are in use, from some atmospheric change ; when
the springs are coated with gold by the electrotype process, no
158 THE PRACTICAL METAL-WORKERS ASSISTANT.
such change is observable, -and the covering, although perfect, may
be so thin as not to compensate for the loss of the blue oxidized
surface.
LESS COMMON EXAMPLES OF HARDENING, AND PRECAUTIONARY
MEASURES. — English writers are famous all over the world for dis-
tributing between themselves and their friends the inventions and
discoveries of the rest of mankind. One of the leading points of
Jacob Perkins's discovery is disposed of in an original manner in
the following paragraph. I thought I was up to every mode in
which they drag in their friends ; but this mode is new to me.
One of the most serious evils in hardening steel, especially in
thick blocks, or those which are unequally thick and thin, is their
liability to crack, from the sudden transition ; and in reference to
hardening razors, a case in point : Mr. mentions it as the ob-
servation and practice of one of his workmen, "that the charcoal
fire should be made up with shavings of leather ;" and upon being
asked what good he supposed the leather could do, this workman
replied, "that he could take upon- him to say that he never had a
razor crack in the hardening since he had used this method, though
it was a frequent occurrence before."
When brittle substances crack in cooling, it always happens
from the outside contracting and becoming too small to contain
the interior parts. But it is known that hard steel occupies more
space than when soft ; and it may easily be inferred that the nearer
the steel approaches to the state of iron, the less will be this in-
crease of dimensions. If, then, we suppose a razor or any other
piece of steel to be heated in an open fire with a current of air
passing through it, the external part will, by the loss of carbon,
become less steely than before ; and when the whole piece comes
to be hardened,, the inside will be too large for the external part,
which will probably crack. But if the piece of steel be wrapped
up ill the cementing mixture, or if the fire itself contain animal
coal, and is put together so as to operate in the manner of that
mixture, the external part, instead of being degraded by this heat,
will be more carbonated than the internal part, in consequence of
which it will be so far from splitting or bursting during its cooling
that it will be acted upon in a contrary direction, tending to
render it more dense and solid.
The cracking which so often occurs on the immersion of steel
articles in water, does not appear to arise so much from any decar-
bonization of the surface merely, as from the sudden condensation
and contraction of a superficial portion of the metal, while the
mass inside remains swelled with the heat, and probably expands
for a moment, on the outside coming in contact with the water.
The file-makers, to save their works from clinking or cracking
partly through in hardening, draw the files through yeast, beer-
grounds, or any sticky material, and then through a mixture of
common salt and animal hoof roasted and pounded. This is cor-
roborative of the above, as in the like manner it supplies a little
HARDENING AND TEMPERING. 159
carbon to the outside, and also renders the steel somewhat harder
and less disposed to crack ; the composition also renders the more
important service of protecting the fine points of the teeth from
being injured by the fire.
An analogous method is now practised in hardening Murphy's
axletrees, which are of wrought-iron, with two pieces of steel
welded into the lower side, where they rest upon the wheels and
sustain the load. The work is heated in an open forge fire, quite
in the ordinary way, and when it is removed, a mixture, principally
the prussiate of potash, is laid upon the steel; the axletree is then
immediately immersed in water, and additional water is allowed to
fall upon it from a cistern. The steel is considered to become very
materially harder for the treatment, and the iron around the same
is also partially hardened.
These are, in fact, applications of the case-hardening process
which is usually applied to wrought-iron for giving it a steely ex-
terior, as the name very properly implies. Occasionally, steel
which hardens but imperfectly, either from an original defect in
the material, or from its having become deteriorated by bad treat-
ment, or too frequent passage through the fire, is submitted to the
case-hardening process in the ordinary way, by inclosing the
objects in iron boxes, as will be explained.
Jacob Perkins's admirable process of transfer engraving may be
thus explained. A soft steel plate was first engraved with the re-
quired subject in the most finished style of art, either by hand or
mechanically, or the two combined, and the plate was then hard-
ened. A decarbonized steel cylinder was next rolled over the
hardened plate by powerful machinery until the engraved impres-
sion appeared in relief, the hollow lines of the original becoming
ridges upon the cylinder. The roller was reconverted to the con-
dition of ordinary steel and hardened, after which it served for
returning the impression to any number of decarbonized plates,
every one of which became absolutely a counterpart of the original ;
and every plate, when hardened, would yield the enormous num-
ber of 150,000 impressions without any perceptible difference
between the first and the last.
In the event of any accident occurring to the transfer roller, the
original plate still existed, from which another or any required
number of rollers could be made, and from these rollers any num-
ber of new plates, all capable of producing as many impressions as
above cited.
The present practice at the Bank of England, introduced by
the late Mr. John Oldham, and now under the superintendence of
his son, Mr. Thomas Oldham, is to anneal at one time four cast-iron
boxes, each containing from three to six steel plates, surrounded
on all sides with fine charcoal mixed with an equal quantity of
chalk and driven in hard.
The reverberatory furnace employed has a circular cast-iron
plate or bed upon which the four boxes are fastened by wedges,
160 THE PEACTICAL METAL -WORKER'S ASSISTANT.
and as the plate revolves very slowly and continually by the steam-
engine employed in working the printing-presses and other ma
chinery, the plates are exposed in the most equal manner to the
heat, and when the proper temperature is attained all the apertures
are carefully closed and luted, to extend the cooling over a space
of at least forty -eight hours.
The surfaces of the cylinders and plates are thus rendered ex-
ceedingly soft, to the depth of about the 32d of an inch, " so as to
become more like lead than any thing else," and thus much of
their surfaces must be turned or planed off; the device is raised in
the transfer-press upon the natural soft steel of the rollers, under a
pressure of some tons, and these are hardened without any inten-
tional application of the case-hardening process, as the simple steel
is undoubtedly very superior in all respects to that which has been
decarbonized and reconverted.
The plates themselves are used in the soft state, as they then
admit of reparation by the transfer rollers ; and the process is
found to be more economical, as the risk of warping is avoided,
and they may be easily repaired. The dates and numbers are at
present printed as a second process by letter-press printing, with
the machines invented by the late Mr. Bramah, and which have
been engraved and described in different books.
In hardening engraved plates, rollers, dies, and similar works, it
is of the greatest importance to preserve the surface unimpaired,
and as steel is very liable to oxidation at the red heat if exposed to
the air for even a few seconds, and which oxidized scale will in
some cases nearly remove, or at any rate injure, the subject produced
upon its surface, it is of great importance to conduct the heating
and cooling with the most complete exclusion of the air.
Mr. Thomas Oldham has, more recently, introduced a mode of
proceeding which appears as near to perfection as possible, and by
it, instead of the works acquiring the ordinary black and gray
tints, and a minute roughness, like the surface of the finest emery
paper, the steel comes out of the water as smooth to the touch as
at first, and mottled with all the beautiful tints seen on case-hard-
ened gun-locks. The method is simply as follows :
The work to be hardened is inclosed in a wrought-iron box with
a loose cover, a false bottom, and with three ears projecting from its
surface about midway ; the steel is surrounded on all sides with car-
bon from leather, driven in hard, and the cover and bottom are
carefully luted with moist clay. Thus prepared, the case is placed
in the vertical position, in a bridle fixed across a great tub, which
is then filled with water almost to touch the false bottom of the
case. The latter is now heated in the furnace as quickly as will
allow the uniform penetration of the heat.
When sufficiently hot, it is removed to its place in the hardening
tub, the cover of the iron box is removed, and the neck or gudgeon
of the cylinder is grasped, beneath the surface of the carbon, with a
long pair of tongs, upon which a coupler is dropped to secure the
HARDENING AND TEMPERING. 161
grasp. It only remains for the individual to hold the tongs with a
glove whilst a smart tap of a hammer is given on their extremity ;
this knocks out the false bottom of the case, and the cylinder and
tongs are instantly immersed in the water ; the tongs prevent the
cylinder from falling on its side, and thus injuring its delicate but
still hot surface. For square plates, a suitable frame is attached by
four slight claws, and it is the frame which is seized by the tongs :
the latter are sometimes held by a chain, which removes the risk
of accident to the individual. In some cases, the work assumes a
striated and mackled appearance, evident to the touch as well as
the sight, and which is to be attributed to an imperfect manufacture
of the steel.
Mr. Oldham informs me that in the Paris Mint, the dies are in-
closed in the soot of burnt wood ; and that in the Royal mint the
dies are hardened by a powerful jet of water. He also adds, that
his workpeople have the impression that steel is reduced to its softest
state by enclosure with lime and ox-gall.
Various methods have been likewise attempted to prevent the
distortions to which work is liable in the operation of hardening,
but without any very advantageous results; for instance, it has
been recommended to harden small cylindrical wires, by rolling
them when heated between cold metallic surfaces to retain them
perfectly straight. This might probably answer, but unfortunately
cylindrical steel wires supply but a very insignificant portion of
our wants.
Another mode tried by Dr. Wollaston was to inclose the piece
of steel in a tube filled with Newton's fusible alloy, the whole to
be heated to redness and plunged in cold water : the object was re-
leased by immersion in boiling water, which melted the alloy, and
the piece came out perfectly unaltered in form, and quite* hard.
This mode is too circuitous for common practice, and the reason
why it is to be always successful is not very apparent.
Is not this a base attempt to drag in Newton and Wollaston ?
To these men the English attribute every thing. Jacob Perkins
was an American to whom all the credit is due. The two Oldhams
were Irishmen, Brunei was a Frenchman, and Bramah was a
German.
Mr. Perkins resorted to a very simple practice with the view of
lessening the distortion of his engraved steel plates by boiling the
water in which they were to be hardened to drive off the air, and
plunging them vertically ; and as the plates were required to be
tempered to a straw color, instead of allowing them to remain in
the water until entirely cold, he removed them whilst the inside
was still hot, and placed them on the top of a clear fire until the
tallow with which they were rubbed, smoked ; the plate was then
returned to the water for a few moments, and so on alternately until
they were quite cold, the surface never being allowed to exceed
the tempering heat.
From various observations, it appears on the whole to be the
11
162 THE PRACTICAL METAL- WORKER'S ASSISTANT.
best in thick works thus to combine the hardening and tempering
processes, instead of allowing the objects to become entirely cold,
and then to reheat them for tempering. To ascertain the time
when the plate should be first removed from the water, Mr. Perkins
heated a piece of steel to the straw color, and dipped it into water
to learn the sound it made ; and when the hardened plate caused the
same sound, it was considered to be cooled to the right degree, and
was immediately withdrawn.
I will conclude these numerous examples and remarks by one
of a very curious, massive, and perfect kind, in which the hardening
is sure to occur without loss of figure, unless the work break under
the process. I refer to the locomotive wheels with hardened steel
tires, which may be viewed as the most ponderous example of
hardening, as the tires of the eight-foot wheels weigh about 10 cwt.,
and consist of about one-third steel, and there seems no reason why
this diameter might not be greatly exceeded.
The materials for the tires are first swaged separately, and then
welded together under the heavy hammer at the steel-works, after
which they are bent to the circle, welded, and turned to certain
gages. The tire is now heated to redness in a circular furnace :
during the time it is getting hot, the iron wheel, previously turned
to the right diameter, is bolted down upon a face-plate ; the tire ex-
pands with the heat, and when at a cherry-red, it is dropped over
the wheel, for which it was previously too small, and is also hastily
bolted down to the surface plate, the whole load is quickly im-
mersed by a swing crane into a tank of water about five feet deep,
and hauled up and down until nearly cold ; the steel tires are not
afterwards tempered.
The spokes are forged out of flat bars with T formed heads ;
these are arranged radially in the founder's mould, whilst the cast-
iron centre is poured around them : the ends of the T heads are
then welded together to constitute the periphery of the wheel or
inner tire, and little wedge-form pieces are inserted where there is
any deficiency of iron.
The wheel is then chucked on a lathe, bored, and turned on the
edge, not cylindrically, but like the meeting of two cones, and
about one quarter of an inch higher in the middle than on the
two edges. The compound tire is turned to the corresponding
form, and consequently larger within or under-cut, so that the
shrinking secures the tire without the possibility of obliquity or
derangement, and no rivets are required. It sometimes happens
that the tire breaks in shrinking when by mismanagement the
diameter of the wheel is in excess.
HARDENING CAST AND WROUGHT-IRON. 163
CHAPTER X,
HARDENING- CAST AND WROUGHT-IRON.
THE similitude of chemical constitution between steel, which
usually contains about one per cent, of carbon, and cast-iron that has
from three to six or seven per cent., naturally leads to the expectation
of some correspondence in their characters, and which, is found to
exist. Thus some kinds of cast-iron will harden almost like steel, but
they generally require a higher temperature ; and the majority of
cast-iron, also like steel, assumes different degrees of hardness,
according to the rapidity with which the pieces are allowed to
cool.
The casting left undisturbed in the mould, is softer than a similar
one exposed to the air soon after it has been poured. Large
castings cannot cool very hastily, and are seldom so hard as the
small pieces, some of which are hardened like steel by the moisture
combined with the moulding sand, and cannot be filed until they
have been annealed after the manner of steel, which renders them
soft and easy to be worked.
Chilled iron-castings present as difficult a problem as the harden-
ing and tempering of steel ; the fact is simply this, that iron cast-
ings, made in iron moulds under particular circumstances, become
on their outer surfaces perfectly hard, and resist the file almost
like hardened steel ; the effect is however superficial, as the chilled
exterior shows a distinct line of demarkation when the objects are
broken.
The production of chilled castings is always a matter of some
uncertainty, and depends upon the united effect of several causes ;
the quality of the iron, the thickness of the casting, the tempera-
ture of the iron at the time of pouring, and the condition or
temperature of the iron mould, which has a greater effect in
" striking in" when the mould is heated than if quite cold : a very
thin stratum of earthy matter will almost entirely obviate the
chilling effect. A cold mould does not generally chill so readily
as one heated nearly to the extent called " black-hot :" but the re-
verse conditions occur with some cast-iron. The hard portion
varies from less than one-sixteenth to more than one-fourth of an
inch in thickness.
There is this remarkable difference between cast-iron thus hard-
ened, and steel hardened by plunging whilst hot into water ; that
whereas the latter is softened again by a dull red-heat, the chilled
castings on the contrary are turned out of the moulds as soon as
the metal is set, and are allowed to cool in the air ; yet although
the whole is at a bright red heat, no softening of the chilled part
takes place. This material has been employed for punches for red-
hot iron; the punches were fixed in cast-iron sockets, from which
164 THE PRACTICAL METAL-WORKER'S ASSISTANT.
they only projected sufficiently to perforate the wheel tires in the
formation of which they were used, and from retaining their hard-
ness they were more efficient than those punches made of steel.
Chilled castings are also commonly employed for axletree boxes,
and naves of wheels, which are finished by grinding only ; also for
cylinders for rolling metal, for the heavy hammers and anvils or
stithies for iron works, the stamp-heads for pounding metallic ores,
etc. Cannon balls, as well as ploughshares, are examples of chilled
castings ; with balls the chilling is unimportant, and occurs alone
from the method essential to giving the balls the required perfec-
tion of form and size.
Malleable iron-castings are at the opposite extreme of the scale,
and are rendered externally soft by the abstraction of their carbon,
whereby they are nearly reduced to the condition of pure malleable
iron, but without the fibre which is due to the hammering and
rolling employed at the forge.
The malleable iron-castings are made from the rich iron, and are
at first as brittle as glass or hardened steel ; they are enclosed in
iron boxes of suitable size, and surrounded with pounded iron-
stone, or some of the metallic oxides, as the scales from the iron
forge, or with common lime, and various other absorbents of carbon,
used either together or separately. The cases, which are sometimes
as large as barrels, are luted, rolled into the ovens or furnaces, and
submitted to a good heat for about five days, and are then allowed
to cool very gradually within the furnaces.
The time and other circumstances determine the depth of the
effect; thin pieces become malleable entirely through; they are
then readily bent, and may be slightly forged ; cast-iron nails and
tacks thus treated admit of being clenched, thicker pieces retain a
central portion of cast-iron, but in a softened state, and not brittU
as at first ; on sawing them through, the skin or coat of soft iron is
perfectly distinct from the remainder.
This mode is particularly useful for thin articles that can be more
economically and correctly cast, than wrought at the forge, aa
bridle-bits, snuffers, parts of locks, culinary and other vessels, pokers
and tongs, many of which are subsequently case-hardened and
polished, as will be explained, but malleable cast-iron should never
be used for cutting-tools.
CASE-HARDENING WROUGHT AND CAST-IRON. — The property of
hardening is not possessed by pure malleable iron ; but I have now
to explain a rapid and partial process of cementation, by which
wrought-iron is first converted exteriorly into steel, and is subse-
quently hardened to that particular depth ; leaving the central
parts in their original condition of soft fibrous iron. The process
is very consistently called case-hardening, and is of great import-
ance in the mechanical arts, as the pieces combine the economy,
strength, and internal flexibility of iron, with a' thin casting of steel;
which, although admirable as an armor of defence from wear or
deterioration as regards the surface, is unfit for the formation of
HARDENING CAST AND WROUGHT- 1 RON. 165
cutting edges or tools, owing to the entire absence of hammering,
subsequent' to the cementation with the carbon. Cast-iron obtains
in like manner a coating of steel, which surrounds the peculiar
shape the metal may have assumed in the iron-foundry and work-
shop.
The principal agents used for case-hardening are animal matters,
as the hoofs, horns, bones, and skins of animals ; these are nearly
alike in chemical constitution; they are mostly charred and
coarsely pounded ; some persons also mix a little common salt
with some of the above. The work should be surrounded on all
sides with a layer from half an inch to one inch thick.
The methods pursued by different individuals do not greatly
differ; for example, the gunsmith inserts the iron work of the gun-
lock, in a sheet-iron case in the midst of bone-dust (often not
burned), the lid of the box is tied on with iron wire, and the joint
is luted wth clay ; it is then heated to redness as quickly as possible,
and retained at that heat from half an hour to an hour, and the
contents are quickly immersed in cold water. The objects sought
are a steely exterior, and a clean surface covered with the pretty
mottled tints, apparently caused by oxidation from the partial
admission of air.
Some of the malleable iron castings, such as snuffers, are case-
hardened to admit of a better polish ; it is usually done with burnt
bone-dust, and at a dull red heat ; they remain in the fire about
two or three hours, and should be immersed in oil, as it does not
render them quite so brittle as when plunged into water. It must
be remembered they are sometimes changed throughout their sub-
stance into an inferior kind of steel, by a process that should in
such instances be called cementation, and not case-hardening, con-
sequently they will not endure violence.
The mechanician and engineer use horns, hoofs, bone-dust, and
leather, and allow the period to extend from two to eight hours,
most generally four or five; sometimes for its greater penetration,
the process is repeated a second time with new carbonaceous
materials. Some open the box and immerse the work in water
direct from the furnace ; others, with the view to preserve a better
surface, allow the box to cool without being opened, and harden
the pieces with the open fire as a subsequent operation; the carbon
once added, the work may be annealed and hardened much the
same as ordinary steel.
When the case-hardening is required to terminate at any par-
ticular part, as a shoulder, the object is left with a band or projec-
tion, the work is allowed to cool without being immersed in water
the band is turned off, and the work when hardened in the open
fire is only affected so far as the original cemented surface
remains.
A new substance for the case-hardening process, but containing
the same elements as those more commonly employed, has of late
years been added, namely, the prussiate of potash (a salt consisting
166 THE PRACTICAL METAL-WORKER'S ASSISTANT.
of two atoms of carbon and one of nitrogen), which is made from a
variety of animal matters.
It is a new application without any change of principle; the
time occupied in this steelifying process is sometimes only min-
utes instead of hours and days, as for example when iron is
heated in the open fire to a dull red, and the prussiate is either
sprinkled upon it or rubbed on in the lump, it is returned to the
fire for a few minutes and immersed in water; but the process is
then exceedingly superficial, and it may if needful be limited to
any particular part upon which alone the prussiate is applied.
The effect by many is thought to be partial or in spots, as if the
salt refused to act uniformly ; in the same manner that water
only moistens a greasy surface in places.
The prussiate of potash has been used for case-hardening the
bearings of wrought-iron shafts, but this seems scarcely worth the
doing.
In the general way, the conversion of the iron into steel, by
case-hardening, is quite superficial, and does not exceed the six-
teenth of an inch ; if made to extend to one-quarter or three-eighths
of an inch in depth, to say the least it would be generally useless,
as the object is to obtain durability of surface, with strength of in-
terior, and this would disproportionately encroach on the strong
iron within. The steel obtained in this adventitious manner is not
equal in strength to that converted and hammered in the usual
way, and if sent in so deeply, the provision for wear would far
exceed that which is required.
Let us compare the case-hardening process with the usual con-
version of steel. The latter requires a period of about seven days,
and a very pure carbon, namely, wood charcoal, of which a minute
portion only is absorbed ; and it being a simple body, when the
access of air is prevented by the proper security of the troughs,
the bulk of the charcoal remains unconsumed, and is reserved for
future use, as it has undergone no change. The hasty and partial
process of cementation is produced in a period commonly less than
as many hours with the animal charcoal, or than as many minutes
with the prussiate of potash ; but all these are compound bodies
(which contain cyanogen, a body consisting of carbon and nitrogen),
and are never used a second time, but on the contrary the process
is often repeated with another dose. It would be, therefore, an
interesting inquiry for the chemist, as to whether the cyanogen is
absorbed after the same manner as carbon in ordinary steel, or
whether the nitrogen assists in any way in hastening the admission
of the carbon, by some as yet untraced affinity or decomposition. It
may happen that the carbon is not essential, as the Indian steel or
wootz is stated to contain alumina, silex, and manganese.
This hasty supposition will apply less easily to cast-iron, which
contains from three to seven times as much carbon as steel, and
although not always hardened by simple immersion, is constantly
under the influence of the case-hardening process ; unless we adopt
APPLICATION OF IRON TO SHIP-BUILDING. 167
the supposition, that the carbon in cast-iron which is mixed with
the metal in the shape of cinder in the blast furnace, when all is in
a fluid state, is in a less refined union than that instilled in a more
aeriform condition in the acts of cementation and case hardening.
CHAPTER XL
ON THE APPLICATION OF IEON TO SHIP-BUILDING.
THERE is probably no branch of industry in which the use of
iron is more important than that of ship-building. The strength,
ductility, and comparative lightness of this material are all in its
favor ; and, although much has been done in the application of
iron to this important purpose, a great deal more remains to be
accomplished. '
Vessels composed of iron plates have been employed for more
than fifty years in the navigation of canals ; but it is not more
than twenty-five or twenty-six since they were first introduced as
sea-going vessels. It is true that the late Mr. Aaron Manby pro-
jected an iron vessel in 1820, which was built in the ensuing year,
and early in 1822 was navigated by Captain (since Admiral Sir
Charles) Napier from London to Havre, and on to Paris; this,
however, was not a sea-going vessel, but an iron steamer con-
structed for the Seine, and which for many years navigated that
river between Paris and Eouen.
From this period little appears to have been done in furtherance
of the application of iron to the construction of ships till 1829-30,
when the introduction of a new system of traction at high veloci-
ties on canals led to new developments ; and from this time to the
present, iron, as a material for ship-building, has been extensively
used, and is increasingly in demand. From 1829 to 1832, iron
ship-building may be considered to have been experimental ; and
the trials conducted by Mr. Fairbairn on the Forth and Clyde
Canal,* simultaneously with those of Mr. John and Mr. McGregor
Laird at Liverpool, led to a new era in the history of ship-building.
Among the first iron vessels for sea-going purposes was one of
small tonnage, built at Manchester for the Forth and Clyde Canal
Company. She was built with paddle-wheels on the quarter near
the stern, and propelled by two high-pressure engines of, collectively,
30 horse-power. This vessel attained great speed, considering the
date at which she was built ; and for many years traded between
Grangemouth and the coast of Fife, round to Dundee.
Previously to the building of the " Manchester," another small
vessel, called the " Lord Dundas," was constructed for the same
* Vide " Remarks on Canal Navigation," by W. Fairbairn. Longman, 1831.
168 THE PRACTICAL METAL-WORKER'S ASSISTANT.
company. She was strictly experimental, and was propelled by a
locomotive engine of 16 horse-power, with 8-inch cylinders. Such
was the lightness of her construction, that the plates were only
l-14th of an inch thick, riveted to light T iron, which formed the
ribs of the hull. This vessel had stern paddles, and was of the
following dimensions : —
Length, 68 feet.
Breadth on beam, 11 feet 6 inches.
Depth, 4 feet 6 inches.
Diameter of paddle-wheel, 9 feet.
"Whole weight, including engine, paddle-wheel, etc., 7 tons 16
cwt.
Draught of water with cargo on board, 16 inches.
The " Lord Dundas" was built in 1830, conveyed through the
streets of Manchester on trucks, and launched into the Irwell,
where numerous trials took place in regard to her speed in narrow
channels, such as canals ; including such other direct experiments
as were likely to result from vessels of this kind propelled by
steam. Subsequently to these trials she was navigated to Liver-
pool, and from thence to Glasgow via the Isle of Man. As this
voyage was rather a perilous one, when the slightness of the vessel's
build and the thinness of her sheathing-plates are considered, and
as it was among the first — if, indeed, it were not the very first —
which indicated the necessity of adjusting the compass in order to
neutralize the local attraction of the material by which it was sur-
rounded, we may probably be permitted to give a^brief narrative of
the circumstances as they occurred during the voyage. The "Lord
Dundas" sailed from Liverpool at four A.M. on a fine morning in
June, 1831, and steered direct for the floating-light. She made the
light in good time, notwithstanding a thick haze in the atmos-
phere, which, during the forenoon, thickened into a dense fog. To-
wards one o'clock land was descried upon the starboard bow, show-
ing apparently that she had made considerable deviation in a west-
erly direction. A dispute arose as to what land it was — one party
contending that it was the western side of the Isle of Man ; the
other, better acquainted with that side of the island, that it was
not. After a considerable contest and examination of the charts,
it was at last discovered that the little vessel was on the north of
Morecambe Bay, approaching the coast of Cumberland. On the
discovery of this error, and in consequence of the frail bark show-
ing symptoms of weakness, from the effects of the swell which was
rolling in from the west, it was considered desirable to look out
for shelter ; and consequently her course was altered in the direc-
tion of the Island of Peel Foundry, where she was sheltered for
the night. On the following morning she crossed to Kamsey>
where the question of the variation of the compass was investi-
gated, and rectified by the simple process of nailing a block of
iron to the deck, in the immediate vicinity of the compass — by
this means neutralizing the local attraction of the iron by which
APPLICATION OF IRON TO SHIP-BUILDING. 169
it was surrounded. After this, the remainder of the voyage from
Ramsey 'to Greenock was effected in a direct course with perfect
safety.
We have noticed these circumstances as illustrating the imper
feet state of our knowledge, as respects the influence of large
masses of iron upon the ship's compass. It has been ascertained
that the angle-iron and T iron ribs, when carried above the deck
so as to form part of the bulwarks, had a remarkable effect upon
the compass, each of them forming, as it were, a separate magnet,
whose influence, unless neutralized by some greater magnetic power,
caused a considerable deviation of the needle, so that it indicated
a point wide of the magnetic north ; and as this deviation altered
with every change of the position of the vessel, no reliance could
be placed upon it. Captain Johnson and Professor Airey, by an in-
teresting series of experiments, ultimately settled this question,
and provided a remedy in the adjustment and correction of the
compass on board iron ships.
The object contemplated by this light vessel and light machinery
was, to ascertain how far quick speeds could be attained upon canals
by steam-power. As much as fourteen miles an hour had been
accomplished by horses, with a tractive power of 352 Ibs. by dyna-
mometer, and that without the least appearance of surge •*• but the
experiments made with the "Lord Dundas" steamer indicated a very
different law, and, under the most favorable circumstances, never
exceeded more than eight to eight and a half miles an hour, and
that with an enormous swell washing over the banks of the canal
in every direction. In fact, the object for which the boat was
built was never attained, and it was found impossible to effect by
steam what was done by horses. It nevertheless led to a mo^
important and a greatly-enlarged branch of industry — namely, th«
construction of iron vessels upon a large scale for ocean traffic.
These experimental vessels, the "Lord Dundas" and the "Man-
chester," already mentioned, in conjunction with the "Alburka,"
and some other vessels, by Messrs. J. Laird and Co., of Liverpool,
may be considered as the first successful attempts in iron ship-
building. Shortly after the completion of these vessels, several
large establishments were founded for this branch of construction,
amongst whom may be enumerated Messrs. W. Fairbairn and Co.,
Millwall, and Messrs. Ditchburn and Mare, Blackwall, London;
Messrs. Laird and Co., Liverpool; Messrs. Tod and McGregor,
Glasgow ; and several others, all of whom were engaged for many
years in the construction of iron ships.
In this chapter we shall be unable to go much into detail, and
must confine ourselves to a few general observations in connection
with the more important application of iron as a material of con-
struction for ocean steamers and sailing vessels, exposed to all the
changes and vicissitudes of wind and tides in the open sea.
* " Remarks on Canal Navigation," page 57.
170
THE PRACTICAL METAL- WORKER'S ASSISTANT.
108.
Fig. 108 exhibits a half cross section of one of Her Majesty's
frigates of the second class, and will, to a certain extent, illustrate
the principles of construc-
tion. It will be seen that
the iron-ship is composed
of a series of frames or ribs,
placed at various distances
apart ; these are connected
together in the interior of
the vessel by transverse
beams, mostly of iron, but
sometimes of wood, which
support the decks. Over
the exterior of the ribs the
iron sheathing-plates are
riveted, so as to form a
continuous water-tight cov-
ering over the entire ex-
terior of the vessel.
RIBS. — One of the ribs is
shown at a a a, Fig. 108 ;
and its section will be seen
in Fig. 109, which is a longi-
tudinal section through the
line b & ; it consists of a
vertical plate c, to which
two angle-irons are riveted,
one at the top and the other
at the bottom. On the
lower angle-iron the sheath-
ing plates d are riveted ; and on the upper, interior plates, somo
Fig. 109. of which in large vessels are
riveted diagonally, so as to
form stringers and braces
from the keelsons round the
bilge to the upper decks.
These ribs are placed at dis-
tances of about fifteen inches
to eighteen inches apart, according to their position in the direc-
Fig. 110. tion of the length of the
ship.
Other kinds of frames
might be used with double
angle-iron, as shown at e ey
in the annexed sketch
(Fig. 110), but they are more expensive; and from the increased
complexity of construction, the extra strength obtained does not
compensate for the difference of cost. Although the frames shown
u^
<
^
c
**r
3i y
V
D
; i.
I
D
APPLICATION OF IRON TO SHIP-BUILDING.
171
in Fig. .109 have come into general use as the most effective and
easy of construction.
KEELS. — This part of the vessel requires to be made exceedingly
strong to resist the pressure or violent shocks to which it is sub-
jected, when a vessel grounds. It is made in various ways,
generally with a false keel, which is riveted on below the ribs by
two angle-irons. The false keel is intended to receive the first
shock in grounding ; and is so arranged that it may even be carried
away without material injury to the true keel. Fig. Ill shows a
method in which it will be seen that the sheathing-plates a a are
bent downwards so as to grasp the side of the keel, which consists
of a massive plate of iron ; whilst the angle-iron of the ribs is bent
upwards at right angles, and is firmly riveted to the vertical keel
plate.
Fig. 111.
Fig 113.
DECKS. — The floorings are supported upon beams extending
from one side of the vessel to the other, and attached at either end
to the ribs or side frames. In the section, Fig. 108, the two upper
decks are supported upon wooden beams, as in an ordinary
Flg' 112t wooden vessel ; but wrought-iron beams may be sub-
stituted for these with great advantage, as
shown at g g.
These deck-beams have been made of vari-
ous forms, the best of which for large ves-
sels is probably that shown in Fig. 112,
which consists of angle irons riveted to the
top and to the bottom of a thin vertical
plate. In some cases a vertical plate, with
two angle-irons at the top and one at the bottom, is used, and has
172 THE PRACTICAL METAL-WORKER'S ASSISTANT.
the advantage of greater simplicity, though the material is not so
well distributed. The box beam (Fig, 113) is employed for sup-
porting the shafts and paddle-boxes of steamers, etc.
EIVETING OF THE PLATES. — In all wrought-iron constructions, the
mode of joining two plates together is the same. When the article
can neither be produced at once from the rolling-mill nor the
steam-hammer, and except in the comparatively few cases where
parts are welded together, they are universally united by rivets. A
series of holes being made through both pieces, a small bolt, with
a head upon one side, is passed through each, and then quickly
hammered down on the other side to another head, so as to grasp
the parts tightly between them. These rivets are usually employed
in a red-hot state, both because they are then more easily ham-
mered down, and because in cooling they contract and draw the
parts together with great force.
Since the introduction of this process, the greatest improvement
has been the substitution of the riveting-machine, invented by Mr.
Fair bairn ; by means of which the object is secured in consider-
ably less time and at less cost, and which completes the union of
the plates with much greater perfection than could possibly be
done by the hand. But this new and very superior process has not
as yet been successfully applied to the riveting of plates for ships.
On comparing the strength of plates with their riveted joints, it
will be necessary to examine the sectional areas taken in a line
through the rivet-holes with the section of the plates themselves.
It is perfectly obvious that in perforating a line of holes along the
edge of a plate, we must reduce its strength ; it is also clear that
the plate so perforated will be to the plate itself, nearly as thu
areas of their respective sections, with a small deduction for the
irregularities of the pressure of the rivets upon the plate; or, in
other words, the joint will be reduced in strength somewhat more
than in the ratio of its section through that line to the solid sec-
tion of the plate. For example, suppose two plates, each two feet
wide and three-eighths of an inch thick, to be riveted together with
ten three-fourth inch rivets. It is evident that out of two feet, the
length of the joint, the strength of the plates is reduced by per-
foration to the extent of seven and a half inches ; and here the
strength of the plates will be to that of the joint as 9 : 6.187*,
which is nearly the same as the respective areas of the solid plate
and that through the rivet-holes; or as 24 : 16'5f. From these
facts it is evident that the rivets cannot add to the strength of the
plates, their object being to keep the two surfaces of the lap in
contact. It may be said that the pressure or adhesion of the two
surfaces of the plates would add to the strength ; but this is not
found to be the case to any great extent, as in almost every in-
stance the experiments indicate the resistance to be in the ratio of
their sectional areas.
* The ratio of the areas. f The ratio of the breadth of metal
APPLICATION OF IRON TO SHIP-BUILDING.
173
Fig. 115.
When this great deterioration of strength at the joint is taken
into account, it cannot but be of the greatest importance that in
structures subjected to such violent strains as ships, the strongest
method of riveting should be adopted. To ascertain this, a long
series of experiments were undertaken by Mr.
Fig. 114. Fairbairn, some of the results of which will be
, — . — - — ^ of interest here. The joint ordinarily employed
/ 1 in ship-building is the lap-
o oooo[ 01 1 joint, shown in Figs. 1 14
and 115. The plates to be
united are made to overlap,
and the rivets are passed
through them, no covering-plates being re-
quired, except at the ends of the plate where
they butt against each other. It is also a common practice to
countersink the rivet-heads on the exterior of the vessel, that the
hull may present a smooth surface for her passage through the
water. This system of riveting is shown in Fig. Ill, where the
rivets of the sheathing-plates are countersunk. This system of
riveting is only used when smooth surfaces are required ; under
other circumstances their introduction would not be desirable, as
they do not add to the strength of the joint, but to a certain ex-
tent reduce it. This reduction is not observable in the experi-
ments ; but the simple fact of sinking the head of the rivet into
the plate, and cutting out a greater portion of metal, must of neces-
sity lessen its strength, and render it weaker than the plain joint
with raised heads.
There are two kinds of lap-joints, those said to be single-riveted
(Fig. 114) and those which are double-riveted (Fig. 115). At first
the former were almost universally employed, but the greater
strength of the latter has since led to their general adoption in the
larger descriptions of vessels. The reason of the superiority is
evident. A riveted joint gives way either by shearing off the rivets
in the middle of their length, or by tearing through one of the
plates in the line of the rivets. In a perfect joint the rivets should
be on the point of shearing just as the plates were about to tear •
but in practice the rivets are usually made slightly too strong.
Hence it is an established rule to employ a certain number of rivets
per lineal foot. If these are placed in a single row, the rivet-holes
so nearly approach each other that the strength of the plates is
much reduced ; but if they are arranged in two lines, a greater
number may be used, and yet more space left between the holes,
and greater strength and stiffness imparted to the plates at the
joint.
174
THE PRACTICAL METAL-WORKERS ASSISTANT.
The results of Mr. Fairbairn's experiments upon the two formg
of joint are given in the following summary :
Strength of single-riveted
Strength of double-riveted
Cohesive strength
of plates.
Breaking-weight in
joints of equal section to
the plates, taken through
the line of rivets.
joints of equal section to
the plates, taken through
the line of rivets.
Ibs. per sq. in.
Breaking-weight in Ibs. per
Breaking-weight in Ibs. per
sq. in.
sq. in.
57,724
45,743
52,352
61,579
.36,606
48,821
58,322
43,141
58,286
50,983
43,515
54,594
51;130
40,249
53,879
49,281
44,715
53,879
43,805
37,161
47,062
Mean
52,486
41,590
53,635
The relative strengths will therefore be —
For the plate . . .
Double- riveted joint .
Single-riveted joint .
1000
1021
791
From the above it will be seen that the single-riveted joints have
lost one-fifth of the actual strength of the plates, whilst the double-
riveted have retained their resisting powers unimpaired. These
are important and convincing proofs of the superior value of the
double joint ; and in all cases where strength is required, this de-
scription of joint should invariably be used.
Comparing these results with those of a former analysis, we
have —
1000 : 1021 and 791*
1000 : 933 and 731
Mean
1000 : 977 and 761
which in practice we may safely assume as the correct value of
each. Exclusive of this difference, we must, however, deduct thirty
per cent, for the loss of metal actually punched out for the reception
of the rivets; and the absolute strength of the plates will then be,
to that of the riveted joints, as the numbers 100, 68, 46. In some
cases, where the rivets are wider apart, the loss sustained is, how-
ever, not so great ; but in boilers and similar vessels where the
rivets require to be. close to each other, the edges of the plates are
weakened to that extent. Taking into consideration the various
circumstances affecting the experimental results, we may fairly
*The cause of the increase of strength in the double-riveted plates may be
attributed to the riveted specimens being made of best, iron ; whereas the
mean strength of the plates is taken from all the irons experimented upon,
dome of inferior quality, which will account for the high value of the double-
riveted joint.
APPLICATION OF IRON TO SHIP-BUILDING. 175
assume the following relative strengths as the value of plates with
their riveted joints.
Taking the strength of the plate at 100
The strength of the riveted joint would then be . 70
And the strength of the single riveted joint . . 56
W'OOD AND IRON AS MATERIALS FOR SHIP-BUILDING. — We shall
consider this point under three heads —
STRENGTH,
DURABILITY,
ECONOMY.
To ascertain the superiority of iron over wood in regard to
strength, let us consider the strains to which a vessel is subjected.
Let us take, for example, a vessel of similar dimensions to the
" Great Western" (the first steamer that successfully crossed the
Atlantic), 212 feet long between the perpendiculars, 35 feet beam,
and 23 feet from the surface of the main deck to the bottom of the
sheathing attached to the keel. Now, considering a vessel of this
Fig. 116.
magnitude, wi*h its machinery and cargo, to weigh 3000 tons, in-
cluding her own weight ; and supposing, in the first instance, that
she is suspended upon two points, A and B, resting on the bow
and stern, at a distance of 210 feet, as shown in Fig. 116 ; we should
then have to calculate, from some formula yet to be determined by
experiment, the ultimate strength of the ship.
To determine this formula with accuracy is a work of research.
In the meantime, we are fortunate in having before us that which
applies with so much certainty to tubular bridges and tubular
girders ; and all that is required in this case will be to ascertain
the correct sectional area of the plates, to prevent the tearing asun-
der of the bottom, and the quantity of material necessary to resist
the crushing force along the line of the upper-deck on the top.
It is true that the necessary data have yet to be determined ; but
the iron ship-builder cannot be far wrong if he assumes the weight
W in the middle (Fig. 116) to be equal to the united weights
of the ship and cargo. This, in the case before us, would give
an ultimate power of resistance of 3000 tonj in the middle, or
6000 tons equally distributed along the ship, with her keel down-
wards.
Assuming these tests, or the calculation derived therefrom, to
be correct, let us now bring the vessel into a totally different po-
176 THE PRACTICAL METAL-WORKER'S ASSISTANT.
sition, as in Fig. 117, having the same weight of cargo on board,
and supported by a wave, which, for the sake of illustration, we
may consider as supporting the vessel upon a single point in the
middle.
Fig. 117.
In this position we find the strain reversed ; and in the place
of the lower part of the hull of a ship being in a state of tension,
it is, on the contrary, in a state of compression, and the whole of
those parts below the neutral axis are subjected to that strain. On
the other hand, the upper part is in a state of tension ; and that
tension, as well as the compressive strain below, will be found to
vary in degree 'in the ratio of the distances from the centre of the
neutral axis a (Fig. 117), round which the forces of tension and
compression revolve. In this supposed position we may venture
to calculate the strengths, in order to ascertain the limit or maxi-
mum of security, and act as if the vessel were placed in trying
circumstances, — either contending with the rolling seas of a hur-
ricane, or suffering the actual suspension of either portion when
taking the ground. In these critical positions, we arrive at the
conclusion, that calculations founded upon the formula for wrought-
iron tubular beams will determine the strength and resisting powers
of an iron ship, and that under every contingency and every cir-
cumstance in which the vessel can be placed. Moreover, it will
give a wide margin of security under all those forms and con-
ditions of peril to which every vessel navigating the ocean is
exposed. We are fully aware that many thousand vessels are now
afloat that would not stand one-third of the tests which we have
taken ; but that is no reason why we should not endeavor to effect
more judicious distribution of the material, in order to attain the
maximum strength, where human life and the fortunes of the
public are at stake.
To show that we have not selected tests which no vessel would
stand, we append the following incidents :
In hauling an iron steamer of nearly 400 tons burthen out of a
temporary basin, she grounded on the extreme end of the bank,
and was left, as the tide receded, with forty feet of her stern en-
tirely without support, and her bow buried in the opposite bank.
On the return of the tide, the vessel floated, and immediately after-
wards she proceeded on her voyage.
A large steamer, the " Vanguard," ran foul of 'a reef of rocks on
the west coast of Ireland, and continued exposed to the swell of
the Atlantic beating her upon them for several days, with com-
APPLICATION OF IRON TO SHIP-BUILDING. 177
paratively little injury, excepting only the corrugation of the
plates along her bottom. She appears to have rested upon a
number of small hard rocks from the stem to the full part of the
vessel just under the paddle-wheels, and from that part to the stern
to have been quite unsupported, except at one place where the
keel was broken. Mr. Clark, who went to examine her, states that
" although she was beating hard for so many days, no part of her
engines was deranged. Her engines were kept constantly at work,
and, in his opinion, are now in as permanent working order as ever
they were. Had the ' Vanguard' been built of wood instead ot
iron, she could not have been saved."
" The ' Boyal George,' one of the iron steamers running between
Liverpool and Glasgow — a 'vessel of unusual length in proportion
to her beam — got on a rock near Greenock at high water, when
loaded with about 150 tons of dead weight besides her engines and
coals, and was left there high and dry during a whole tide without
sustaining any injury. She rested nearly on her centre ; and all
who saw her were of opinion that no timber vessel could have re-
mained in that position without breaking her back." *
We might adduce numerous other instances in which iron ves-
sels have, without material injury, stood the strains which must
have caused a timber vessel to go to pieces. An iron ship is
united by riveting into a single firm mass ; whilst a wooden vessel
is composed of an innumerable number of pieces, all imperfectly
joined together, but which are, nevertheless, dependent on each
other for support, — so that if any one gives way, the stability of
all the rest is endangered.
In his paper on iron as a material for ship -building, Mr. Fail
bairn gives the following results of some experiments on the com-
parative strength of wood and iron, when subjected to pressure
from a blunt instrument placed at right angles to the surface of
the plate. It will be seen that, in these experiments, an endeavor
was made to place the material in circumstances similar to those
mentioned above, where the vessel is beating upon hard and unequal
ground. In these experiments, the wrought-iron plates were fastened
upon a frame of cast-iron, one foot square inside, and one foot six
inches outside. The sides of the plate, when hot, were twisted
round the frame, to which they were firmly bolted. The force to
burst it was applied in the centre by a bolt of iron, terminating in
a hemisphere three inches in diameter.
* Summary of Results.
Ibs. Mean : Ibs.
In Experiment I., a plate one-fourth of an inch
thick was burst by 13,789 )
In Experiment IL, a plate one-fourth of an inch [• 16/779
thick was burst by 19,769 )
* Grantham " On Iron as a Material for Ship-Building."
178 THE PRACTICAL METAL-WORKER'S ASSISTANT.
Ibs. Mean : Ibs,
In Experiment III., a plate half an inch thick
was burst by ........... 37,519
In Experiment IV., a plate half an inch thick
was burst by ........... 37,928 j
Here the strengths are as the depths, a half- inch plate requiring
double the weight to produce fracture that had previously burst a
quarter-inch plate.
The experiments on wood were made upon good English oak, of
the same width as the iron plates. The specimens were laid upon
solid planks twelve inches asunder, and by the same apparatus the
rounded end of the three-inch pin was forced through them.
Summary of JResults.
Ibs. Mean : Ibs.
Strength of planks 3 inches thick ..... 18,941
3 " " ..... 16,925
440fi
1J " ..... 4,280 j
Here the strength to resist crushing follows the ratio of the square
of the depth, as is found to be the case in the transverse fracture of
rectangular bodies of constant breadth and span. The experiments
show conclusively the superiority of iron in ordinary cases.
DURABILITY. — The durability of iron ships is now established
beyond a doubt; and it is generally admitted that they remain fit
for service longer than those of timber. At first it was thought
that the action of salt-water would cause a rapid oxidation, and very
soon disable them ; indeed, oxidation has been the rock -ahead of
every iron ship for the last twenty years. The evil has been ex-
aggerated ; and there are instances of iron ships built twenty years
ago, which are still in existence with no sensible appearance of cor-
rosion or decay, and, what is of equal importance, without having
required repairs, if we except a few coats of oil-paint, or the appli-
cation of some other anti-corrosive substance to neutralize the
effects of the sea-water. Nature, however, comes to our assistance
in this, as in almost every other attempt in the constructive arts,
and seems to confirm the proverb, "A bright sword never rusts;"
for it is with iron ships as with iron rails — when in constant use
there is little, if any, appearance of oxidation.
ECONOMY. — Mr. Grantham, in the work already quoted, comes
to the conclusion that iron vessels are on the whole less expensive
in construction than similar vessels of wood. But assuming that,
when built in the best manner, they cost about the same, still, the
iron ship has great advantages. The strength of iron is so great
that we are enabled to use a much thinner shell than with wood ;
and hence there is much more stowage room. The cost of main-
taining an iron vessel, repairs, etc., are very small ; whilst in a tiiu-
METALS AND ALLOYS. 179
ber vessel they amount to a large sum. Iron vessels are not sub-
ject to a dry rot ; and we have already seen that they will remain
under severe strain comparatively uninjured, when a timber vessel
would go to pieces,
It is necessary here to advert to the use of iron as applied to
vessels of war. There cannot exist a doubt as to the advantages to
be derived from iron as a material for ship-building, and it is as
desirable in the navy as in the merchant service ; but the great draw-
back to its application is the effect of shot upon iron plates, and the
consequent danger to the vessel if not regularly " armored," but merely
constructed of iron like a merchantman. This danger does not arise
so much from point-blank shot entering the ship at high velocities,
as from shot ranging from a distance, and which strike the vessel
with a reduced force. In the first case the shot penetrates and
passes through the plates, making a perforation equal in diameter
to the shot ; but a half-spent shot when it arrives, not only pene-
trates the side of the ship, but tears up the plates to a distance of
some feet on every side. It is from this that the chief danger is to
be apprehended. It is useless here to point out that which is, now
so very apparent to all well informed persons, that the successful
application of iron in the building of powerful vessels of war, dur-
ing the present contest in the United States — eventful in so very
many respects — has opened a new era in ocean warfare. So great
is this revolution, that the navies of the old world are now rendered
comparatively harmless and consequently useless ; and the United
States, with her "New Ironsides,7' "Dunderberg," "Dictator," "Puri-
tan," " Eoanoke," and other iron-clads, is to-day not only the first
military, but the first naval power in the world.
CHAPTER XII.
THE METALS AND ALLOYS MOST COMMONLY USED.
WE have now to consider the following metals : Antimony, Bis-
muth, Copper, Gold, Lead, Mercury, Nickel, Palladium, Platinum,
Rhodium, Silver, Tin, and Zinc. Unlike iron and steel, they do
not admit of being hardened beyond that degree which may be
produced by simple mechanical means, such as hammering, rolling,
etc., neither (with the exception of platinum) do. they submit to
the process of welding.
On the other hand, their fusibility offers an easy means of unit-
ing and combining many of these metals with great readiness,
either singly, or in mixtures of two or several kinds, which are
called alloys By the process of founding, any required form may
180 THE PRACTICAL METAL-WORKER'S ASSISTANT.
be given to the fusible metals and alloys : their malleability and
ductility are also turned to most useful and varied account ; and
by partial fusion neighboring metallic surfaces may be united,
sometimes per se, but more generally by the interposition of a still
more fusible metal or alloy called solder.
The author intends therefore to commence with a brief notice of
the physical characters and principal uses of the thirteen metals
before named, and of their more important alloys. Tables of the
cohesive force and of the general properties of metals will be next
added to avoid the occasional necessity for reference to other
works.
These tables will be followed by some remarks on alloys, which as
regards their utility in the arts, may be almost considered as so
many distinct metals ; this will naturally lead to the processes of
melting, mixing and casting the metals ; a general notice and ex-
planation of many works, taking their origin in the malleable and
ductile properties, will then follow ; and the consideration of the
metals, and of materials from the three kingdoms, will be con-
cluded by a descriptive account of the modes of soldering.
DESCRIPTION
OF THE
PHYSICAL CHARACTER AND USES
OP
THE METAIS AND ALLOYS
COMMONLY EMPLOYED IN
THE MECHANICAL AND USEFUL ARTS.
ANTIMONY is of a silvery white color, brittle and crystalline* in
its ordinary texture. It fuses at about 800°, or at a dull
red heat, and is volatile at a white heat. Its specific gravity
is 6.712.
ANTIMONY expands on cooling ; it is scarcely used alone,
except in combination with similar bars of other metals for
producing thermo-electricity : but antimony, which in the
metallic state is frequently called " regulus," is generally
combined with a large portion of lead, and sometimes with
tin, and other metals. m See LEAD and TIN.
" Antimony and tin,"mixed in equal proportions, form a
moderately hard, brittle, and very brilliant alloy, capable of
receiving an exquisite polish, and not easily tarnished by
exposure to the air ; it has been occasionally manufactured
into speculums for telescopes. Its s. g. is less than the
mean of its constituent parts."
METALS AND ALLOYS. 181
BISMUTH is a brittle white metal with a slight tint of red : its
specific gravity is 9.822. It fuses at 476° to 507°, and
always crystallizes on cooling. According to Chaudet, pure
bismuth is somewhat flexible, A cast bar of the metal,
one-tenth of an inch diameter, supports, according to Mus-
chenbroeck, a weight of forty-eight-pounds. Bismuth is
volatile at a high heat, may be distilled in close vessels. It
transmits heat more slowly than most other metals, perhaps
' in consequence of its texture.
BISMUTH is scarcely used alone, but it is employed for
imparting fusibility to alloys, thus :
8 bismuth, 5 lead, 3 tin,. constitute a fusible alloy, which
melts at 212° F.
2 bismuth, 1 lead, 1 tin, a fusible alloy, which melts at
201° R
5 bismuth, 3 lead, 2 tin, when combined melt at 1-99°.
8 bismuth, 5 lead, 4 tin, 1 type metal, constitute the fusi-
ble alloy used on the Continent for producing the beautiful
casts of the French medals, by the clichee process. The
metals should be repeatedly melted and poured into drops
until they are well mixed.
1 bismuth, and 2 tin, make an alloy found to be the most
suitable for rose-engine and eccentric-turned patterns, to be
printed from after the manner of letter-press. The thin
plates are cast upon a cold surface of metal or stone, upon
which a piece of smooth paper is placed, and then a metal
ring; the alloy should neither burr nor crumble; if proper,
it turns soft and silky ; when too crystalline, more tin should
be added.
All these alloys must be cooled quickly to avoid the sep-
aration of the bismuth ; they are rendered more fusible by
a small addition of mercury.
COPPER, with the exception of titanium, is the only metal which
has a red color; it has much lustre, is very malleable and
ductile, and exhales a peculiar smell when warmed or rub-
bed. It melts at a bright-red or dull white heat at a tem-
perature intermediate between the fusing points of silver and
gold=1996° Fahr. Its specific gravity varies from 8.86 to
8.89 ; the former being the least density of cast copper, the
latter the greatest of rolled or hammered copper.
COPPER is used alone for many important purposes, and
very extensively for the following : namely, sheathing and
bolts for ships, brewing, distilling, and culinary vessels.
Some of the fire boxes for locomotive engines, boilers for
marine engines, rollers for calico-printing and paper-mak-
ing, plates for the use of engravers, etc.
182 THE PRACTICAL METAL -WORKER^ ASSISTANT.
Copper is used in alloying gold and silver, for coin, plate,
etc., and it enters with zinc and nickel into the composition
of German silver. Copper alloyed with one-tenth of its
weight of arsenic is so similar in appearance to silver, as to
have been substituted for it.
The alloys of copper, which are very numerous and im-
portant, are principally included under the general name,
Brass. In the more common acceptation, brass means the
yellow alloy of copper, with about half its weight of zinc ;
this is often called by engineers " yellow brass."
Copper alloyed with about one-ninth its weight of tin, is
the metal of brass ordnance, which is very generally called
gun-metal ; similar alloys used for the " brasses" or bearings
of machinery, are called by engineers, hard brass, and also
gun- metal ; and such alloys when employed for statues and
medals are called bronze. The further addition of tin leads
to bell metal, and speculum metal, which are named after
their respective uses ; and when the proportion of copper is
exceedingly small the alloy constitutes one kind of pewter.
Copper, when alloyed with nearly half its weight of lead,
forms an inferior alloy, resembling gun-metal in color, but
very much softer and cheaper, lead being only about one-
fourth the value of tin, and used in much larger propor-
tion.
This inferior alloy is called pot-metal, and also cock-
metal, because it is used for large vessels and measures, for
the large taps or cocks for brewers, dyers and distillers, and
those of smaller kinds for household use.
Generally, the copper is only alloyed with . one of the
metals, zinc, tin, or lead ; occasionally with two, and some-
times with the three in various proportions. In many cases,
the new metals are carefully weighed according to the quali-
ties desired in the alloy, but random mixtures more fre-
quently occur, from the ordinary practice of filling the
crucible in great part with various pieces of old metal, of
unknown proportions, and adding a certain quantity of new
metal to bring it up to the color and hardness required.
This is not done solely from motives of economy, but also
from an impression which appears to be very generally
entertained, that such mixtures are more homogeneous than
those composed entirely of new metals, fused together for
the first time.
The remarks I have to offer on these copper alloys will
be arranged in the tabular form, in four groups ; and to
make them as practical as possible, they will be stated in
the terms commonly used in the brass-foundry. Thus,
when the founder is asked the usual proportions of yellow
brass, he will say, 6 to 8 oz. of zinc (to every pound of
copper being implied). In speaking of gun-metal, he
METALS AND ALLOYS. 183
wou d not say, it had one-ninth, or 11 per cent, of tin, but
simply that it was 1J, 2, or 2J oz. (of tin), as the case might
be ; so that the quantity and kind of the alloy, or the addi-
tion to the pound of copper, is usually alone named : and
to associate the various ways of stating these proportions,
many are transcribed in the forms in which they are else-
where designated.
ALLOYS OF COPPER AND ZINC ONLY.
The marginal numbers denote the ounces of zinc added to every pound of copper.
J- to J oz. Castings are seldom made of pure copper, as under
ordinary circumstances it does not cast soundly ; about half
an ounce of zinc is usually added, frequently in the shape
of 4 oz. of brass to every pound of copper ; and by others
4 oz. of brass are added to every two or three pounds of
copper.
1 to 1J- oz. Gilding metal, for common jewelry : it is made by
mixing 4 parts of copper with 1 of calamine brass ; or
sometimes 1 Ib. of copper with 6 oz. of brass. The sheet
gilding-metal will be found to match pretty well in color
with the cast gun-metal, which latter does not admit of
being rolled ; they may be therefore used together when
required.
3 oz. Bed sheet brass, made at Hegermiihl, or 5J- parts copper;
1 zinc.
3 to 4 oz. Bath metal, pinchbeck, Mannheim gold, similor, and
alloys bearing various names, and resembling inferior jewel-
er's gold greatly alloyed with copper, are of about this pro-
portion : some of them contain a little tin ; now, however,
they are scarcely used.
6 oz. Brass, that bears soldering well.
6 oz. Bristol brass is said to be of this proportion.
8 oz. Ordinary brass, the general proportion ; less fit for solder-
ing than 6 oz., it being more fusible.
8 oz. Is generally the ingot brass, made by simple fusion of the
two metals.
9 oz. This proportion is the one extreme of Muntz's patent
sheathing. See lOf.
lOf oz. Muntz's metal, or 40 zinc and 60 copper. "Any propor-
tions," says the patentee, "between the extremes, 50 zinc
and 50 copper, and 37 zinc 63 copper, will roll and work at
the red-heat ;" but the first-named proportion, or 40 zinc to
60 copper is preferred.
The metal is cast into ingots, heated to a red-heat, and
rolled and worked at that heat into ships' bolts and other
fastenings and sheathing.
12 oz. Spelter-solder for copper and iron is sometimes made in
this proportion ; for brass work, the metals are generally
mixed in equal parts. See 16 oz.
184: THE PRACTICAL METAL-WORKER'S ASSISTANT.
12 GZ. Pale yellow metal, fit for dipping in acids, is often made
in this proportion.
16 oz. Soft spelter-solder, suitable for ordinary brass work, is
made of equal parts of copper and zinc. About 14 Ibs. of
each are melted together and poured into an ingot mould
with cross ribs, which indents it into little squares of about
2 Ibs. weight ; much of the zinc is lost. These lumps are
afterwards heated nearly to redness upon a charcoal fire,
and are broken up one at a time with great rapidity on an
anvil or in an iron pestle and mortar. The heat is a critical
point ; if too great, the solder is beaten into a cake or coarse
lumps and becomes tarnished ; when the heat is proper, it is
nicely granulated, and remains of a bright yellow color ; it
is afterwards passed through a sieve. Of course the ultimate
proportion is less than 16 oz. of zinc.
16 oz. Equal parts is the one extreme of Muntz's patent sheath-
ing. See lOf.
16 J oz. Mosaic gold, which is dark-colored when first cast, but on
dipping assumes a beautiful golden tint. When cooled and
broken, all yellowness must cease, and the tinge vary from
reddish fawn or salmon color, to a light purple or lilac, and
from that to whiteness. The proportions are stated as from
52 to 58 zinc to 50 of copper, or 16J- to 17 oz. to the pound.
32 oz. or 2 zinc to 1 copper, a bluish-white, brittle alloy, very
brilliant, and so crystalline that it may be pounded cold in a
mortar.
128 oz. or two ounces of copper to every pound of zinc ; a hard
crystalline rnetal differing but little from zinc, but more tena-
cious ; it has been used for laps or polishing disks.
REMARKS ON THE ALLOYS OF COPPER AND ZINC.
These metals seem to mix in all proportions.
The addition of zinc continually increases the fusibility,
but from the extremely volatile nature of zinc, these alloys
cannot be arrived at with very strict regard to proportion.
The red color of copper slides into that of yellow brass at
about 4 or 5 oz. to the pound, and remains little altered
unto about 8 or 10 oz. ; after this it becomes whiter, and
when 32 oz. of zinc are added to 16 of copper, the mixture
has the brilliant silvery color of speculum metal, but with a
bluish tint.
These alloys, from about 8 to 16 oz. to the pound of
copper, are extensively used for dipping, as in an enormous
variety of furniture work ; in all cases the metal is annealed
before the application of the scouring or cleaning processes,
and of the acids, bronzes and lackers subsequently used.
The alloys with zinc retain their malleability and ductility
well, unto about 8 or 10 ounces to the pound ; after this, the
crystalline character slowly begins to prevail. The alloy of
METALS AND ALLOYS. 185
2> zinc and 1 copper, before named, may be crumbled in a
mortar when cold.
The ordinary range of good yellow brass, that files and
turns well, is from about 4J to 9 oz. to the pound. ^ With
additional zinc, it is harder and more crystalline ; with less,
more tenacious, and it hangs to the file like copper ; the
range is wide, and small differences are not perceived.
ALLOYS OF COPPER AND TIN ONLY.
The marginal numbers denote the ounces of tin added to every pound of copper.
Ancient Copper and Tin Alloys.
} oz. Ancient bronze nails, flexible, or 20 copper, 1 tin.
1 j oz. Soft bronze, or . . 9 to 1
2 oz. Medium bronze, or 8 to 1
2 J oz. Hard bronze, or . 7 to 1
6 to 8 oz. Ancient mirrors.
According to Pliny, as quoted
by Wilkinson.
Ancient weapons and tools,
by various analyses, or 8 to 15
per cent, tin ; metals from 8 to
12 per cent, tin, with two parts
zinc added to each 100, for
^ improving the bronze color.
Modern Copper and Tin Alloys.
1 oz. Soft gun metal, that bears drifting, or stretching from a
perforation.
1 J oz. A little harder alloy, fit for mathematical instruments ; or
12 copper and 1 very pure grain tin.
1 J oz. Still harder, fit for wheels to be cut with teeth.
1 J to 2 oz. Brass ordnance, or 8 to 12 per cent, tin ; but the gen-
eral proportion is one-ninth part of tin.
2 oz. Hard bearings for machinery.
2J oz. Very hard bearings for machinery. By Muschenbroek's
Tables it appears that the proportion 1 tin and 6 copper is
the most tenacious alloy ; it is too brittle for general use,
and contains 2 J oz. to the pound of copper.
3 oz. Soft musical bells.
3J oz. Chinese gongs and cymbals, or 20 per cent. tin.
4 oz. House bells.
4J oz. Large bells.
5 oz. Largest bells.
7J to 8J oz. Speculum metal. Sometimes one ounce of brass is
added to every pound as the means of introducing a trifling
quantity of zinc, at other times small proportions of silver
are added; the employment of arsenic is by some recom-
mended.
The object agreed upon by all experimentalists appears
to be the exact saturation of the copper with the tin, and
the proportionate quantities differ very materially (in this
186 THE PRACTICAL METAL-WORKER'S ASSISTANT.
and all other alloys}, according to the respective degrees of purity
of the metals : for the most perfect alloys to this group,
Swedish copper, and grain tin, should be used.
When the copper is in excess, it imparts a red tint easily
detected ; when the tin is in excess, the fracture is granu-
lated and also less white. The practice is to pour the
melted tin into the fluid copper when it is at the lowest
temperature that a mixture by stirring can be effected, then
to pour the mixture into an ingot and to complete the com-
bination by remelting in the most gradual manner, by put-
ting the metal into the furnace as soon almost as the fire is
lighted : trial is made of a little piece taken from the pot
immediately prior to pouring.
32 oz. of tin to one pound of copper, makes the alloy called by
the pewterers " temper" which is added in small quantities
to tin, for some kinds of pewter, called " tin and temper" in
which the copper is much less than 1 per cent.
REMARKS ON THE ALLOYS OF COPPER AND TIN ONLY.
These metals seem to mix in all proportions.
The addition of tin continually increases the fusibility,
although when it is added cold it is apt to make the copper
pasty, or even to set in a solid lump in the crucible.
The red color of the copper is not greatly impaired in
those proportions used by the engineer, namely, up to about
2J ounces to the pound; it becomes grayish white at 6, the
limit suitable for bells, and quite white at about 8, the
speculum metal ; after this, the alloy becomes of a bluish
cast.
The tin alloy is scarcely malleable at 2 ounces, and soon
becomes very hard, brittle, and sonorous ; and when it has
ceased to serve for producing sound, it is employed for
reflecting light.
The tough tenacious character of copper under the tools
rapidly gives way ; alloys of 1 J cut easily, 2 J assume about
the maximum hardness without being crystalline ; after this
they yield to the file by crumbling in fragments rather than
by ordinary abrasion in shreds, until the tin very greatly
predominates, as in the pewters, when the alloys become the
more flexible, soft, malleable, and ductile, the less copper
they contain.
ALLOYS OF COPPER AND LEAD ONLY.
The marginal numbers denote the ounces of lead added to every pound of copper.
2 oz A red-colored and ductile alloy.
4 oz. Less red and ductile ; neither of these is so much used as
the following, as the object is to employ as much lead as
possible
METALS AND ALLOYS. 187
6 oz. -Ordinary pot-metal, called dry pot-metal, as this quantity
of lead will be taken up without separating on cooling ; this
is brittle when warmed.
7 oz. This alloy is rather short, or disposed to break.
8 oz. Inferior pot-metal, called wet pot-metal, as the lead partly
oozes out in cooling, especially when the new metals are
mixed ; it is therefore always usual to fill the crucible in
part with old metal, and to add new for the remainder. This
alloy is very brittle when slightly warmed. More lead can
scarcely be used, as it separates on cooling.
REMARKS ON THE ALLOYS OF COPPER AND LEAD ONLY.
These metals mix in all proportions until the lead amounts
to nearly half, after this they separate in cooling.
The addition of lead greatly increases the fusibility.
The red color of copper is soon deadened by the lead ;
at about 4 ounces to the pound the work has a bluish leaden
hue when first turned, but changes in an hour or so to that
of a dull gun-metal character.
When the lead does not exceed about 4 oz. the mixture
is tolerably malleable, but with more lead it soon becomes
very brittle and rotten : the alloy is greatly inferior to gun-
metal, and is principally used on account of the cheapness
of the mixture, and the facility with which it is turned and
filed.
ALLOYS OF COPPER, ZINC, TIN, AND LEAD, ETC.
This group refers principally to gun-metal alloys, to which more or less zinc
is added by many engineers. The quantity of tin in every pound of the
alloy, which is expressed by the marginal numbers, principally determines
the hardness.
M. Keller's statues at Versailles are found, as the mean
of four analyses, to consist of:
Copper . . . . 91.40 or about 14| ounces.
Zinc 5.53 " 1 ounce.
Tin 1.70 " Of «
Lead 1.37 " O "
In 100 parts or the 16 ounces.
1J to 2J oz. tin to 1 Ib. copper used for bronze medals, or 8 to 15
per cent, tin, with the addition of 2 parts in each 100 of
zinc, to improve the color.
The modern so-called bronze medals of our Mint are of
pure copper, and are afterwards bronzed superficially.
1J oz. tin, J zinc to 16 oz. copper. Pumps and works requiring
great tenacity.
188 THE PRACTICAL METAL-WORKER'S ASSISTANT.
1J oz. tin, 2 oz. brass, 16 oz. copper ( For wheels to be cut into
If " 2 " 16 « f teeth.
2 " aj " 16 " For turning work.
2J " 1J " 16 " For nuts of coarse threads
and bearings.
The engineer who uses these five alloys recommends
melting the copper alone ; the small quantity of brass is
then melted in another crucible, and the tin in a ladle, — the
two latter are added to the copper when it has been removed
from the furnace. The whole are stirred together and
poured into the moulds without being run into ingots. The
real quantity of tin to every pound of copper is about one-
eighth oz. less than the number stated, owing to the addition
of the brass, which increases the proportion of copper.
If oz. tin, If oz. zinc, to 1 Ib. copper. This alloy, which is a tough,
yellow, brassy, gun-metal, is used for general purposes. It
is made by mixing 1J Ib. tin, 1J- Ib. zinc, and 10 Ibs. of
copper. The alloy is first run into ingots.
2J oz. tin, J oz. zinc, to 1 Ib. copper. Used for bearings to sustain
great weights.
2J oz. tin, 2J oz. zinc, to 1 Ib. copper, were mixed by Chantrey,
and a razor was made from the alloy. It proved nearly as
hard as tempered steel, and exceedingly destructive to new
files, and none others would touch it.
I oz. tin, 2 oz. zinc, 16 oz. brass. Best hard white metal for
buttons.
J oz. tin, 1J oz. zinc, 16 oz. brass. Common white metal for
buttons.
1.0 Ibs. tin, 6 Ibs. copper, 4 Ibs. brass, constitute white solder. The
copper and brass are first melted together, the tin is added,
and the whole stirred and poured through birch twigs into
water to granulate it ; it is afterwards dried and pulverized
cold in an iron pestle and mortar. This white solder was
introduced as a substitute for silver solder in making gilt
buttons. Another button solder consists of 10 parts cop-
per, 8 of brass, and 12 of spelter or zinc.
KEMARKS ON ALLOTS OF COPPER, ZINC, TIN, AND LEAD, ETC.
ORDINARY YELLOW BRASS (copper and zinc) is rendered
very sensibly harder, so as not to require to be hammered,
by a small addition of tin, say j- or J oz. to the Ib. On the
other hand by the addition of J to J oz. of lead, it becomes
more malleable, and casts more sharply. Brass becomes a
little whiter for the tin, and redder for the lead. The ad-
dition of nickel to copper and zinc constitutes the so-called
German silver.
GUN METAL (copper and tin) very commonly receives H
small addition of zinc ; this makes the alloy mix better, and
METALS AND ALLOYS. 189
to lean to the character of brass by increasing the mallea-
bility without materially reducing the hardness. The zinc,
which is sometimes added in the form of brass, also im-
proves the color of the alloy both in the recent and bronzed
states. Lead in small quantity improves the ductility of
gun-metal, but at the expense of its hardness and color ; it
is seldom added. Nickel has been proposed as an addition
to gun-metal by O'Donovan, of Dublin, and antimony by
his countryman, Dr. Ure.
POT METAL (copper and lead) is improved by the addition
of tin, and the three metals will mix in almost any pro-
portions. When the tin predominates, the alloy so much
the more nearly approaches the condition of gun-metal.
Zinc may be added to pot metal in very small quantity, but
when the zinc becomes a considerable amount, the copper
takes up the zinc, forming a kind of brass, and leaves the
lead at liberty, and which in great measure separates in
cooling. Zinc and lead are also very indisposed to mix
alone, although a little arsenic assists their union by " kill-
ing" the lead, as in shot metal. Antimony also facilitates
the combination of pot metal; 7 lead, 1 antimony, and 16
copper, mixed perfectly well the first fusion, and the alloy
was decidedly harder than 4 lead and 16 copper, and ap-
parently a better metal. " Lead and antimony, though in
small quantity, have a remarkable effect in diminishing the
elasticity and sonorousness of the copper alloys."
GOLD is of a deep and peculiar yellow color. It melts at a
bright red heat, equivalent to 2016° of Fahrenheit's scale,
and when in fusion appears of a brilliant greenish color. Its
specific gravity is 19.3. It is so malleable that it may be
extended into leaves which do not exceed the one two
hundred and eighty-two thousandth of an inch in thickness,
or a single grain may be extended over 56 square inches of
surface. This extensibility of the metal is well illustrated
by gilt buttons, 144 of which are gilt by 5 grains of gold,
and less than even half that quantity is adequate to giving
them a very thin coating. It is also so ductile that a grain
may be drawn out into 500 feet of wire. The pure acids
have no action upon gold.
GOLD in the pure or fine state is not employed in bulk
for many purposes in the arts, as it is then too soft to be
durable. The gold foil used by dentists for stopping decayed
teeth is perhaps as nearly pure as the metal can be obtained ;
it contains about 6 grains of alloy in the pound troy, or the
one -thousandth part. Every superficial inch of this gold foil
or leaf weighs } of a grain, and is 42 times as thick as the
leaf used for gilding.
The wire for gold lace prepared by the refiners for gold-
lace manufacturers, requires equally fine gold, as when alloyed
190 THE PRACTICAL METAL-WORKERS ASSISTANT.
it does not so well retain its brilliancy. The gold in the
proportion of about 100 grains to the pound troy of silver,
or of 140 grains for double-gilt wire, is beaten into sheets as
thin as paper; it is then burnished upon a stout red-hot
silver bar, the surface of which has been scraped perfectly
clean. When extended by drawing, the gold still bearing
the same relation as to quantity, namely, the 57th part of
the weight becomes of only one-third the thickness of or-
dinary gold-leaf used for gilding. In water-gilding, fine gold
is amalgamated with mercury, and washed over the gild-
metal (copper and tin), the mercury attaches itself to the
metal, and when evaporated by heat it leaves the gold behind
in the dead or frosted state : it is brightened with the burn-
isher. By the electrotype process a still thinner covering
of pure gold may be deposited on silver, steel, and other
metals. French watch-makers introduced this method of
protecting the steel pendulum springs of marine chronometers
and other time-pieces from rust.
Fine gold is also used for soldering chemical vessels made
of platinum.
GOLD ALLOYS.
Gold-leaf for gilding contains from 3 to 12 grains of alloy
to the oz., but generally 6 grains. The gold used by re-
spectable dentists, for plates, is nearly pure, but necessarily
contains about 6 grains copper in the oz. troy, or one 80th
part; others use gold containing upwards of one-third of
alloy ; the copper is then very injurious.
With copper, gold forms a ductile alloy of a deeper color,
harder and more fusible than pure gold ; this alloy, in the
proportion of 11 of gold to 1 of copper, constitutes English
standard gold; its density is 17.157, being a little below the
mean, so that the metals slightly expand on combining.
One troy pound of this alloy is coined into 46f g English
sovereigns, or 20 troy pounds into 934 sovereigns and a
half. (The pound was formerly coined into 44 guineas and
a half). The standard gold of France consists of 9 parts of
gold and 1 of copper.
For Gold Plate the French have three different standards:
92 parts gold, 8 copper ; also 84 gold, 16 copper ; and 75
gold, 25 copper.
In England, the purity of gold is expressed by the terms
22, 18, 16, 12, 8, carats, etc. The pound troy is supposed
to be divided into 24 parts, and the gold, if it could be ob-
tained perfectly pure, might be called 24 carats fine.
The " Old Standard Gold," or that of the present British
currency, is called fine, there being 22 parts of pure gold
to 2 of copper.
METALS AND ALLOYS.
'•
/
' J91
* / ' t
The " New Standard," for watch-cases, etc. is 18 carats of
fine gold, and 6 of alloy. No gold of inferior quality /6/18
carats, or the " New Standard," can receive the Hall mark •/
and gold of lower quality is generally described by its 9010
mercial value.
The alloy may be entirely silver, which will give a green
color, or entirely copper for a red color, but the copper and
silver are more usually mixed in the one alloy according to
the taste and judgment of the jeweler.
The following alloys of gold are transcribed from the memoranda
of the proportions employed by a practical jeweler of considerable
experience. When it is otherwise expressed, it will be understood
all these alloys are made with fine gold, fine silver, and fine copper,
obtained direct from the refiners. And to insure the standard
gold passing the test of the Hall, 3 or 4 grains additional of gold
are usually added to every ounce.
First Group. Different kinds of gold that are finished b;y polish-
ing, burnishing, etc., without necessarily requiring to be
colored :
The gold of 22 carats fine is so little used, on account of its
expense and greater softness, that it has been purposely
omitted.
18 carats, or New Standard
gold, of yellow tint :
15 dwt. 0 grs. gold.
2 dwt. 18 grs. silver.
2 dwt. 6 grs. copper.
20 dwt. 0 grs.
18 carats of red tint :
15 dwt. 0 grs. gold.
1 dwt. 18 grs. silver.
3 dwt. 6 grs. copper.
20 dwt. 0 grs.
16 carats or Spring gold : this,
when drawn or rolled very
hard, makes springs little
inferior to those of steel.
oz. 16 dwt. gold.
6 dwt. silver.
12 dwt. copper.
2 oz. 14 dwt.
or 1.12
— A
— .12
2. 8
$15 gold of yellow tint, or the
fine gold of the jewelers; 16
carats nearly :
1 oz. 0 dwt. gold.
7 dwt. silver.
5 dwt. copper.
1 oz. 12 dwt.
$15 gold of red tint, or 16
carats :
1 oz. 0 dwt. gold.
2 dwt. silver.
8 dwt. copper.
1 oz. 10 dwt.
Second Group. Colored golds : these all require to be submitted
to the process of wet-coloring, which will be explained ; they are
192
THE PRACTICAL METAL-WORKER'S ASSISTANT.
used in much smaller quantities, and require to be very exactly
proportioned.
Full red gold :
5 dwt. gold.
5 dwt. copper.
10 dwt.
Eed gold :
10 dwt. gold.
1 dwt. silver,
4 dwt. copper.
15 dwt.
Green gold :
5 dwt. 0 grs. gold.
21 grs. silver.
5 dwt. 21 grs.
Gray gold : (Platinum is also
called gray gold by jewel-
ers.)
3 dwt. 15 grs. gold.
1 dwt. 9 grs. silver.
5 dwt. 0 grs.
Blue gold : scarcely used :
5 dwt. gold.
5 dwt. steel filings.
10 dwt.
Antique gold, of a fine green-
ish-yellow color :
18 dwt. 9 grs. gold, or 18. 9
21 grs. silver, — 1. 3
18 grs. copper, — .12
20 dwt. 0 grs.
20. 0
Third Group. Gold solders : these are generally made from gold
of the same quality and value as they are intended for, with a small
addition of silver and copper, thus :
Solder for $15 gold:*
Solder for 22 carat gold:
1 dwt. 0 grs. of 22 carat gold.
2 grs. silver.
1 gr. copper.
1 dwt. 3 grs.
Solder for 18 carat gold :
1 dwt. 0 grs. of 18 carat gold.
2 grs. silver.
1 gr. copper
1 dwt. 3 grs.
1 dwt. 0 grs. of $15 gold.
10 grs. silver.
8 grs. copper.
1 dwt. 18 grs.
Solder for $10 gold: but mid-
dling silver solder is more
generally used.
1 dwt. fine gold.
1 dwt. silver.
2 dwt. copper.
4 dwt.
Dr. Hermstadt's imitation of gold, which is stated not only to re-
semble gold in color, but also in specific gravity and ductility, con-
* By others, 4 grains of brass are added to the solder ; it then fuses beauti-
fully and is of good color. Zinc is sometimes added to 'Other good solders to
increase their fusibility, the zinc (or brass when used) should be added at the
last moment, to lessen the volatilization of the zinc.
METALS AND ALLOYS. 193
sists of 16 parts of platinum, 7 parts of copper, and 1 zinc, put in a
crucible, covered with charcoal powder, and melted into a mass.
Gold alloyed with platinum is also rather elastic, but the plati-
num whitens the alloy more rapidly than silver.
LEAD appears to have been known in the earliest ages of the
world. Its color is bluish white ; it has much brilliancy, is
remarkably flexible and soft, and leaves a black streak on
paper : when handled it exhales a peculiar odor. It melts
at about 612°, and by the united action of heat and air, is
readily converted into an oxide. Its specific gravity, when
pure, is 11.44:5 ; but the lead of commerce seldom exceeds
11.35.
LEAD is used in a state of comparative purity for roofs,
cisterns, pipes, vessels for sulphuric acid, etc. Ships were
sheathed with lead and with wood, from before the Christian
era to 1450, after which wood was more commonly employed,
and in 1790 to 1800 copper sheathing became general ; of
late years, lead with a little antimony has likewise been
used, also an alloy of copper and zinc and galvanized sheet
iron. The most important alloys of lead are those employed
for printers' type, namely, about
3 lead, 1 antimony, for the smallest, hardest and most
brittle types.
4 lead, 1 antimony, for small, hard, brittle types.
5 lead, 1 antimony, for types of medium size.
6 lead, 1 antimony, for large types.
7 lead, 1 antimony, for the largest and softest types.
In addition to lead and antimony, type-metal also contains
from 4 to 8 per cent, of tin, and sometimes 1 to 2 per cent,
of copper ; but as old metal is always used with the new,
the proportions are not exactly known.
Stereotype-plates are made of 20 parts of lead, 4 of
antimony, and 1 of tin.
Baron Wetterstedt's patent sheathing for ships, consists
of lead with from 2 to 8 per cent, of antimony ; about 3
per cent, is the usual quantity. The alloy is rolled into
sheets.
Similar alloys, and those of lead and tin in various prep-
arations, are much used for emery wheels and grinding-
tools of various forms by the lapidary, engineer, and others.
The latter also employs these readily-fused alloys for tem-
porary bearings, guides, screw nuts, etc.
Organ pipes consist of lead alloyed with about half its
quantity of tin to harden it. The mottled or crystalline ap-
pearance so much admired shows an abundance of tin.
Shot metal is said to consist of 40 Ibs. of arsenic to one
ton of lead.
13
194 THE PRACTICAL METAL-WORKER'S ASSISTANT.
In casting sheet-lead, the metal was poured from a swing-
trough upon a long and nearly horizontal table covered
with a thin layer of coarse damp sand, previously levelled
with a metal rule or strike. The thickness of the fluid
metal was determined by running the strike along the table
before the lead cooled, the excess being thus swept into a
spill-trough at the lower end of the table ; but the sheet-
lead now more commonly used, is cast in a thick slab, and
reduced between laminating rollers ; it is known as " milled
lead."
The metal for organ-pipes is prepared by allowing the
metal to escape through the slit in a trough, as it is slid
along a horizontal table, so as to leave a trail of metal be-
hind it ; the thickness of the metal is regulated by the width
of the slit through which it runs, and the rapidity of the
traverse ; a piece of cloth or ticken is stretched upon the
casting table. The metal is planed to thickness, bent up
and soldered into the pipes.
Lead pipes are cast as hollow cylinders and drawn out
upon triblets ; they are also cast of indefinite length with-
out drawing. A patent was taken out for casting a sheath
of tin within the lead, but it has been abandoned.
Lead shot are cast by letting the metal run through a
narrow slit, into a species of colander at the top of a lofty
tower ; the metal escapes in drops, which for the most part
assume the spherical form before they reach the tank of
water into which they fall at the foot of the tower, and this
prevents their being bruised. The more lofty the tower,
the larger the shot that can be produced ; the good and the
bad shot are separated by throwing small quantities at a
time upon a smooth board nearly horizontal, which is
slightly wriggled ; the true or round shot run to the bottom,
the imperfect ones stop by the way, and are thrown aside
to be re-melted ; the shot are afterwards riddled or sifted
for size, and churned in a barrel with black lead.
MERCURY is a brilliant white metal, having much of the color
of silver, whence the terms hydrargyrum, argentum vivum,
and quicksilver. It has been known from very remote ages.
It is liquid at all common temperatures ; solid and malleable
at 40° F., and contracts considerably at the moment of con-
gelation. It boils and becomes vapor at about 670°. Its
specific gravity at 60° is 13.5. In the solid state its den-
sity exceeds 14. The specific gravity of murcurial vapor
is 6.976.
MERCURY is used in the fluid state for a variety of philo-
sophical instruments, and for pressure gages for steam-en-
gines, etc. It is sometimes, although rarely, employed for
rendering alloys more fusible ; it is used with tin-foil for
METALS AND ALLOY! 195
silvering looking-glasses, and it has been employed as a
substitute for water in hardening steel. Mercury forms
amalgams with bismuth, copper, gold, lead, palladium, sil-
ver, tin, and zinc.
Mercury is commonly used for the extraction of gold and
silver from their ores by amalgamation, and also in water-
gilding.
NICKEL is a white brilliant metal, which acts upon the magnetic
needle, and is itself capable of becoming a magnet. Its
magnetism is more feeble than that of iron, and vanishes at
a heat somewhat below redness, 630°. It is ductile and
malleable. Its specific gravity varies from 8.27 to 8.40
when fused, and after hammering, from 8.69 to 9.00. It is
not oxidized by exposure to air at common temperatures,
but when heated in the air it acquires various tints like
steel ; at a red-heat it becomes coated by a gray oxide.
NICKEL is scarcely used in the simple state, but princi-
pally used together with copper and zinc, in alloys that are
rendered the harder and whiter the more nickel they contain ;
they are known under the names of albata, British plate,
electrum, German silver, pakfong, teutanag, etc. : the pro-
portions differ much according to price ; thus the
Commonest are 3 to 4 parts nickel, 20 copper, and 16
zinc.
Best . are 5 to 6 parts nickel, 20 copper, and 8
to 10 zinc.
About two-thirds of this metal is used for articles resem-
bling plated goods, and some of which are also plated ; the
remainder is employed for harness, furniture, drawing and
mathematical instruments, spectacles, the tongues for accor-
dions, and numerous other small works.
The white copper of the Chinese, which is the same as
the German silver of the present day, is composed of 31.6
parts of nickel, 40.4 of copper, 25.4 of zinc, and 2.6 of iron,
17.48 53.39 13.0 — .
The white copper manufactured at Sutil in the duchy of
Saxe Hildburghausen, is said by Keferstein to consist of
copper 88.000, nickel 8.753, sulphur with a little antimony
0.750, silex, clay, and iron 1.75. The iron is considered to
be accidentally introduced into these several alloys along
with the nickel, and a minute quantity is not prejudicial.
Iron and steel have been alloyed with nickel ; the former
(the same as the meteoric iron which always contains nickel)
is little disposed to rust : whereas the alloy of steel with
nickel is worse in that respect than steel not alloyed.
PALLADIUM is of a dull-white color, malleable and ductile,
specific gravity is about 11.3, or 11.86 when laminated.
196 THE PRACTICAL METAL-WORKER'S ASSISTANT.
fuses at a temperature above that required for the fusion
of gold.
PALLADIUM is a soft metal, but its alloys are all harder
than the pure metal. With silver it forms a very tough
malleable alloy, fit for the graduations of mathematical in-
struments, and for dental surgery, for which it is much used
by the French. With silver and copper, palladium makes
a very springy alloy, used for the points of pencil-cases,
inoculating lancets, tooth-picks, or any purpose where elas-
ticity and the property of not tarnishing are required.
Thus alloyed it takes a high polish. Pure palladium is
not fusible at ordinary temperatures, but at a high tempera-
ture it agglutinates so as to be afterwards malleable and
ductile.
This useful metal has recently been found in some abun-
dance in the gold ores of the Minas Gerae's district. Pal-
ladium is calculated thoroughly to fulfil many of the
purposes to which platinum and gold are applied in the
useful arts, and from its low specific gravity it may be ob-
tained at about half the price of an equal bulk of platinum,
and at one- eighth that of gold ; and it equally resists the
action of mineral acids and sulphuretted hydrogen.
Palladium was used in the construction of the balances
for the United States Mint.
PLATINUM is a white metal, extremely difficult of fusion, and
unaltered by the joint action of heat and air. It varies in
density from 21 to 21.5, according to the degree of mechan-
ical compression which it has sustained. It is extremely
ductile, but cannot be beaten into such thin leaves as gold
and silver.
The particles of the generality of the metals, when sep-
arated from the foreign matters with which they are com-
bined, are joined into solid masses by simple fusion ; but
platinum being nearly infusible when pure, requires a very
different treatment.
The platinum is first dissolved chemically, and it is then
thrown down in the state of a precipitate ; next it is partly
agglutinated in the crucible into a spongy mass, and is then
compressed whilst cold in a rectangular mould by means
of a powerful fly -press or other means, which in operating
upon 500 ounces, converts the platinum into a dense block
afcout 5 inches by 4, and 2J inches thick. This block is
heated in a smith's forge, with two tuyeres meeting at an
angle, at which spot the platinum is placed, amidst the
charcoal fire. When it has reached the, welding point, or
almost a blue heat, it receives one blow under a heavy drop,
or a vertical hammer somewhat like a pile-driving engine ;
it then requires to be reheated, and it thus receives a fresh
METALS AND ALLOYS. 197
"blow about every twenty minutes, and in a week or ten days
it is sufficiently welded or consolidated on all sides to admit
of being forged into bars, and converted into sheets, rods,
or wires by the ordinary means.
The motive for operating upon so great a quantity is for
making the large pans for concentrating sulphuric acid in
only two or three pieces, which are soldered together with
fine gold. In France 2000 ounces are sometimes welded
into one mass, so that the vessels may be absolutely entire.
For small quantities the treatment is the same, but in
place of the drop, the ordinary flatter and sledge-hammer
are used.
PLATINUM is exceedingly tough and tenacious, and
"hangs to the file worse than copper;" on which account
when it is used for the graduated limbs of mathematical
instruments, the divisions should be cut with a diamond-
point, which is the best instrument for fine graduations of
all kinds, and for ruling grounds, or the lined surfaces for
etchings.
PLATINUM is employed in Eussia for coin. This valuable
metal is also used for the touch-holes of fowling-pieces, and
in various chemical and philosophical apparatus in which
resistance to fusion or to the acids is essential.
The alloys of platinum are scarcely used in the arts;
that with a small quantity of copper is employed in Paris
for dental surgery.
" Dr. Yon Eckart's alloy contains platinum 2.40, silver
3.53, and copper 11.71. It is highly elastic, of the same
specific gravity as silver, and not subject to tarnish ; it can
be drawn to the finest wire from J- of an inch diameter
without annealing, and does not lose its elasticity by an-
nealing. It is highly sonorous, and bears hammering red-
hot, rolling and polishing."
Dr. Eyan added to silver one-fourth of its weight of
platinum, and he considers that it took up one-tenth its
weight. The alloy became much harder than silver, capable
of resisting the tarnishing influences of sulphur and hydro-
gen, and was fit for graduations.
An alloy of platinum with ten parts of arsenic is fusible
at a heat a little above redness, and may therefore be cast in
moulds. On exposing the alloy to a gradually-increasing
temperature in open vessels, the arsenic is oxidized and ex-
pelled, and the platinum recovers its purity and infusibility.
Tin also so greatly increases the fusibility of platinum
that it is hazardous to solder the latter metal with tin-
solder, although gold is so used.
Platinum, as well as gold, silver and copper, are deposited
by the electrotype process; and silver plates thus platinized
are employed in the galvanic battery.
198 THE PRACTICAL METAL-WORKER'S ASSISTANT.
RHODIUM is a white metal very difficult of fusion. Its specific
gravity is about 11; it is extremely hard ; when pure the
acids do not dissolve it.
Rhodium has been long employed for the nibs of pens,
which have been also made of ruby, mounted on shafts of
spring gold. These kinds have had to endure for the last
seven or eight years the rivalry of " Hawkins's Everlasting
Pen," of which latter, the author, from many months' con-
stant use, can speak most favorably. "The everlasting
pen," says the inventor, "is made of gold tipped with a
natural alloy, which is as much harder than rhodium as
steel is harder than lead ; will endure longer than the ruby ;
yields ink as freely as the quill ; is easily wiped ; and if
left unwiped is NOT CORRODED."
Mr. Hawkins employs the natural alloy of iridium and
osmium, two scarce metals discovered by Mr. Tenriant, of
Belfast, amongst the grains of platinum. The alloy is not
malleable, and is so hard as to require to be worked with
diamond powder. The metals rhodium, iridium, and os-
mium, are not otherwise employed in the arts than for pens,
although steel has been alloyed with rhodium.
The inventor of the gold pen, Mr. Hawkins, is an
American.
SILVER is of a more pure white than any other metal. It has
considerable brilliancy, and takes a high polish. Its specific
gravity varies between 10.4, which is the density of cast
silver, and 10.5 to 10.6, which is the density of rolled or
stamped silver. It is so malleable and ductile, that it may
be extended into leaves not exceeding the ten-thousandth
of an inch in thickness, and drawn into wire much finer
than a human hair. Silver melts at a bright-red heat, at
1873° of Fahrenheit's scale, and when in fusion appears
extremely brilliant.
SILVER is but little used in the pure unalloyed state, on
account of its extreme softness, but it is generally alloyed
with copper in about the same proportion as in our coin,
and none of inferior value can receive the " Hall mark."
Diamonds are set in fine silver, and in silver containing
3 to 12 grs. of copper in the ounce. The work is soldered
with pure tin.
The sheet metal for plated works is prepared by fitting
together very truly a short stout bar of copper and a thin-
ner plate of silver. When scraped perfectly clean they are
tied strongly together with binding wire, and united by
partial fusion without the aid of solder. .The plated metal
is then rolled out, and the silver always remains perfectly
united and of the same proportional thickness as at first.
Additional silver may be burnished on hot, when the sur-
METALS AND ALLOYS. 199
faces are scraped clean, as explained under gold. This is
done either to repair a defect, or to make any part thicker
for engraving upon, and the uniformity of surface is re-
stored with the hammer. In addition to its use for articles
of luxury, the important service of copper plated with
silver for the parabolic reflectors of light-houses must not
be overlooked. These are worked to the curve with great
perfection by the hammer alone.
Plated spoons, forks, harness, and many other articles, are
made of iron, copper, brass, and German silver, either cast
or stamped into shape. The objects are then filed and
scraped perfectly clean ; and fine silver, often little thicker
than paper, is attached with the aid of tin solder and heat.
The silver is rubbed close upon every part with a bur-
nisher.
The electrotype process is also used for plating several
of the metals with silver, which it does in the most uniform
and perfect manner. The silver added is charged by weight
at about three times the price of the metal. The German
silver, or albata, is generally used for the interior substance,
as when the silver is partially worn through the white alloy
is not so readily detected as iron or copper.
SILVER ALLOYS.
The alloy with copper constitutes plate and coin. By the
addition of a small proportion of copper to silver, the
metal is rendered harder and more sonorous, while its color
is scarcely impaired. Even with equal weights of the two
metals, the compound is white. The maximum of hard-
ness is obtained when the copper amounts to one-fifth of
the silver.
" For silver plate, the French proportions are 9J parts
silver, J copper ; and for trinkets, 8 parts silver, 2 copper."
Silver solders are made in the following proportions :
Hardest silver solder, 4 parts fine silver, and 1 part
copper ; this is difficult to fuse, but is occasionally employed
for figures.
Hard silver solder, 3 parts silver, and 1 part brass wire,
which is added when the silver is melted, to avoid wasting
the zinc.
Soft silver solder for general use, 2 parts fine silver, and
1 part brass wire. By some few, f part of arsenic is ad-
ded, to render the solder more fusible and white, but it be-
comes less malleable ; the arsenic must be introduced at the
last moment, with care to avoid its fumes.
Silver is also soldered with tin solder (2 tin, 1 lead), and
with pure tin.
Silver and mercury are used in the plastic metallic stop
ping for teeth.
200 THE PRACTICAL METAL-WORKERS ASSISTANT
TIN has a silvery-white color with a slight tint of yellow ; it is
malleable, though sparingly ductile. Common tin-foil,
which is obtained by beating out the metal, is not more than
one-thousandth of an inch in thickness, and what is termed
white Duck metal is in much thinner leaves. Its specific
gravity fluctuates from 7.28 to 7.6, the lightest being the
purest metal. When bent it occasions a peculiar crackling
noise, arising from the destruction of cohesion amongst . its
particles.
When a bar of tin is rapidly bent backwards and for-
wards, several times successively, ic becomes so hot that it
cannot be held in the hand. When rubbed, it exhales a
peculiar odor. It melts at 442°, and, by exposure to heat
and air, is gradually converted into a protoxide.
Pure tin is commonly used for dyers' kettles; it is also
sometimes employed for the bearings of locomotive car-
riages and other machinery. This metal is beaten into very
large sheets, some of which measure 200 by 100 inches,
and are of about the thickness of an ordinary card : the
small sized foil is stated not to exceed one-thousandth of an
inch in thickness. The metal is first laminated between
rollers, and then spread one sheet at a time upon a large
iron surface or anvil, by the direct blows of hammers with
very long handles ; great skill is required to avoid beating
the sheets into holes. The large sheets of tin-foil are only
used for silvering looking-glasses by amalgamation with
mercury. Tin-foil is also used for electrical purposes. The
amalgam used for electrical machines, is 7 tin, 3 zinc, and 2
mercury.
TIN is drawn into wire, which is soft and capable of be-
ing bent and unbent many times without breaking ; it is
moderately tenacious and completely inelastic. Tin tube is
extensively used for gas fitting and many other purposes
by Le Roy & Co., of New York ; it has been recently in-
troduced in an ingenious manner for the formation of very
cheap vessels, for containing artists' and common colors,
besides numerous other solid substances and fluids, required
to be hermetically sealed, with the power of abstracting
small quantities.
Tin plate is an abbreviation of tinned iron plate ; the
plates of charcoal iron are scoured bright, pickled, and im-
mersed in a bath of melted tin covered with oil, or with a
mixture of oil and common resin ; they come out thoroughly
coated. Tinned iron wire is similarly prepared : there are
several niceties in the manipulation of each of these pro-
cesses, which cannot be noticed in this place.
Tin is one of the most cleanly and sanatory of metals,
and is largely consumed as a coating for culinary vessels,
METALS AND ALLOYS. 20 i
although the quantity taken up in the tinning is exceed-
ingly small, and which was noticed by Pliny.
Tin imparts hardness, whiteness and fusibility to many
alloys, and is the basis of different solders, and other im-
portant alloys, all of which have a low power of conduct-
ing heat.
PEWTER is principally tin ; mostly lead is the only addi-
tion, at other times copper, but antimony, zinc, etc., are used
with the above, as will be separately adverted to. The ex-
act proportions are unknown even to those engaged in the
manufacture of pewter, as it is found to be the better mixed
when it contains a considerable portion of old metal to
which new metal is added by trial.
Some pewters are made very common ; when cast they
are black, shining and soft ; when turned, dull and bluish.
Other pewters only contain one fifth or one-sixth of lead ;
these when cast are white, without gloss and hard ; such
are pronounced very good metal, and are but little darker
than tin. The French legislature sanctions the employment
of 18 per cent, of lead with 82 of tin as quite harmless in
vessels for wine and vinegar.
The finest pewter, frequently called "tin and temper,"
consists mostly of tin, with a very little copper, which
makes it hard and somewhat sonorous, but the pewter be-
comes brown-colored when the copper is in excess. The
copper is melted, and twice its weight of tin is added to it,
and from about J to 7 Ibs. of this alloy or the "temper,"
are added to every block of tin weighing from 360 to 390
pounds.
Antimony is said to harden tin and to preserve a more
silvery color, but is little used in pewter. Zinc is employed
to cleanse the metal rather than as an ingredient ; some stir
the fluid pewter with a thin strip, half zinc and half tin ;
others allow a small lump of zinc to float on the surface
of the fluid metal whilst they are casting, to lessen the
oxidation.
White metal is said to consist of 3 J cwt. of block tin, 28
Ibs. antimony, 8 Ibs. copper, and 8 Ibs. brass ; it is cast into
ingots and rolled into very thin sheets.
Tin solders are very much used in the arts.
1 tin, 3 lead, the coarse plumber's solder, melts at about
500 F.
2 tin, 1 lead, the ordinary or fine tin solder, melts at about
360 F.
ZINC is a bluish-white metal, with considerable lustre, rather hard,
of a specific gravity of about 6.8 in its usual state, but, when
drawn into wire, or rolled into plates, its density is aug-
mented to 7 or 7.2. In its ordinary state at common tern-
202
peratures it is tough, and with difficulty broken by blows
of the hammer. It becomes very brittle when its tempera-
ture approaches that of fusion, which is about 773°; but at
a temperature a little above 212°, and between that and
300°, it becomes ductile and malleable, and may be rolled
into thin leaves, and drawn into moderately fine wire,
which, however, possesses but little tenacity. When a mass
of zinc, which has been fused, is slowly cooled, its fracture
exhibits a lamellar and prismatic crystalline texture.
ZINC, which is commercially known as " Spelter," although
it is always brittle when cast, has of late years taken its
place amongst the malleable metals ; the early stages of its
manufacture into sheet, foil and wire are stated to be con-
ducted at a temperature somewhat above that of boiling
water ; and it may be afterwards bent and hammered cold,
but it returns to its original crystalline texture when re-
melted. It has been applied to many of the purposes of
iron, tinned-iron, and copper; it is less subject to oxidation
from the effects of the atmosphere than the iron, and much
cheaper, although less tenacious, ductile, or durable than
the copper. The sheet metals when bent lengthways of the
sheet (or like a roll of cloth), are less disposed to crack
than if bent sideways ; in this respect zinc and sheet iron
are the worst : the risk is lessened when they are warmed.
Zinc is applied as a coating to preserve iron from rust.
Zinc mixed with one-twentieth its weight of speculum
metal may be melted in an iron ladle, and made to serve
for some of the purposes of brass, such as common chucks.
The alloy is sufficient to modify the crystalline character,
but reserves the toughness of the zinc ; it will not, however,
bear hammering either hot or cold. Four atoms of zinc
and one of tin, or 133.2 and 57.9, make a hard, malleable,
and less crystalline alloy.
Biddery ware, manufactured at Biddery, a large city, 60
miles N.W. of Hyderabad in the East Indies, and also at
Benares, is said to consist of copper 16 oz., lead 4 oz., and
tin 2 oz., melted together ; and to every 3 oz. of this alloy,
16 oz. of spelter or zinc are added. The metal is used as
an inferior substitute for silver, and resembles some sorts
of pewter.
The foregoing alloys are mostly derived from actual
practice, and although it has been abundantly shown that
alloys are most perfect, when mixed according to atomic
proportions, or by multiples of their chemical equivalents,
yet this excellent method is little adopted, owing to various
interferences.
For example, it is in most cases necessary from an eco-
nomic view, to mix some of the old alloys (the proportions of
which are uncertain), along with the new metals. In most
METALS AND ALLOYS. 203
cases also, unless the fusion and refusion of the alloys are
conducted with considerably more care than ordinary prac-
tice ever attains, or really demands, the loss by oxidation
completely invalidates any nice attempts at proportion ; and
which proportions can be alone exactly arrived at when the
combined metals are nearly or quite pure.
The chemical equivalents of the metals upon the hydro-
gen scale are appended ; thus for mixtures of any metals, say
tin and zinc, instead of taking arbitrary quantities, one
atom of tin or 57.9 parts by weight, should be combined
with 1, 2, 3, 4 or 5 atoms of zinc, or any multiple of 32.3
parts, and so with all other metals.
In the following table the first column of figures denotes the
comparative strength of the metals, glass being considered as unity ;
thus steel of razor temper is nearly 16 times as strong as glass of
eqiial size ; and by the second column, it is seen that a bar of steel
one inch square is pulled asunder by a load of 150,000 Ibs.
NOTE. — The following Alloys having been omitted in their proper places
are here inserted together.
BABBITT'S ANTI-ATTRITION METAL — DIRECTIONS FOR PREPARING AND FITTING. —
Melt 4 Ibs. of copper, add. by degrees, 12 Ibs. best quality Banca tin, 8 Ibs.
regulus of antimony, and 12 Ibs. more of tin while the composition is in a
melted state.
After the copper is melted and 4 or 5 Ibs. of tin have been added, the heat
should be reduced to a dull red, to prevent oxidation ; then add the remainder
of the metal as above. In melting the composition it is better to keep a
small quantity of powdered charcoal on the surface of the metal. The above
composition is called "hardening." For lining the boxes, take one Ib. of
this hardening and melt it with 2 Ibs. of Banca tin, which produces the lining
metal for use. Thus the proportions for lining metal are 4 Ibs. of copper, 8 Ibs.
of regulus of antimony, and 96 Ibs. of Banca tin.
The article to be lined, having been cast with a recess for the lining, is to
be nicely fitted to a former, which is made of the same shape as the bearing.
Drill a hole in the article for the reception of the metal, say a half or three-
quarters of an inch, according to the size of it. Coat over the part not to be
tinned with a clay wash, wet the part to be tinned with alcohol, and sprinkle
on it powdered sal ammoniac ; heat it till a fume arises from the sal ammo-
niac, and then immerse it in melted Banca tin, taking care not to heat it so
that it will oxidize.
After the article is tinned, should it have a dark color, sprinkle a little sal
ammoniac on it, which will make it of a bright silver color. Cool it gradually
in water, then take the former to which the article has been fitted, and coat it
over with a thin clay wash, and warm it so that it will be perfectly dry ; heat
the article until the tin begins to melt, lay it on the former and pour in the
metal, which should not be so hot as to oxidize, through the drilled hole,
giving it a head, so that as it shrinks it will fill up. After it has sufficiently
cooled remove the former.
A shorter method may be adopted when the work is light enough to handle
quickly, namely — When the article is prepared for tinning, it may be im-
mersed in the lining metal instead of the tin, brushed lightly in order to
remove the sal ammoniac from the surface, placed immediately on the former
and lined at the same heating.
FENTON'S ANTI-FRICTION METAL. — 7| parts of grain zinc, 7£ of purified zinc,
and 1 of antimony.
ALLOY OP THE STANDARD MEASURE USED BY GOVERNMENT. — 576 parts copper,
89 of tin, and 48 of brass (yellow, 2 copper to 1 of zinc).
TUTENAGUE. — 8 parts of copper, 5 of zinc, and 3 of nickel.
EXPANSION METAL.— 9 parts of lead, 2 of antimony, and 1 of bismuth.
204
TABLES OF THE COHESIVE FORCE OF SOLID BODIES.
TABLE I. — METALS.
(h) and (I) mark the highest and lowest result which Muschenbroek obtained from
each kind of iron.
METALS.
Specific cohe-
sion. Glass I.
•S-Sc
«-S 2
*§5
•S^a
0 «8.5
£$
11
OQ to
Hardness.
AUTHORITY.
STEEL.
15.927
150,000
7.78 to
Muschenbroek, Encyclo. Brit., art.
Soft
12.739
120,000
7.84
,?,
Strength.
Idem.
IRON.
Wire ..
12.004
113,077
German bar,markBR(h)
Swedish bar (h)
German bar, mark L (h)
Wire
9.880
9.445
9.119
9.108
93,069
88,972
85,000
85,797
Muschenb. Int. ad Phil. Nat. i. 426.
Idem.
Idem.
Buffon, OZuvres deGauthey, ii. 153.
Bar
8.964
84,443
8.794
82,839
Muschenb. Int. ad Phil. Nat. i. 426.
8.685
81,901
Idem.
Bar
8.581
80,833
4.
Soufflot Rondelet's L'Art de Batir,
Bar
8.492
80,000
jt-1
0
•4—
05
iv. 500.
Edin. Encyclo., art. Bridge, 544.
Oosement bar (h)
Cable .
8.142
7.752
76,697
73 024
«o
i>l
s
00
Muschenb. Intr. ad Phil. Nat. i. 426.
Annals of Phil vii 320
German bar, mark L (I)
German bar, common...
Swedish bar 1 ,.v
Oosement bar j * '
Bar of best quality
7.382
7.339
7.296
7 006
69,538
69,133
68,728
66 000
a
o
Cl
1
Muschenb. Intr. ad Phil. Nat. i. 426.
Idem.
Idem.
Rumford Phil Mag x 51.
6.621
62,369
Muschenb Intr. ad Phil. Nat. i. 426.
German bar, markBR(l)
Bar*
6.514
6.480
61,361
61,041
Idem.
Perronet 03uv. de Gauthey, ii. 154.
Bar of good quality
Cable
5.839
5.787
55,000
54 513
Rumford, Phil. Mag. x. 51.
Annals of Phil x 311
5.306
49,982
Rondelet, L'Art. de Batir, iv. 502.
medium fineness....
coarse-grained
CAST IRON.
French.. .. . .....^
3.618
2.172
7 470
34,081
20,460
70 367
Idem.
Idem.
Navier (Euv de Gauthey ii 150
7 250
68,295
7 807
Muschenb Intr. ad Phil. N»t.i.417.
French, soft .t
6 754
63 622
Rondelet L'Art de Batir iv. 514
English J
5.520
52,000
Banks, Gregory's Mechan. i. 129.
French J
5.412
50,981
Ex. i.
L'Ecole des Ponts, etc. Gaut. ii. 150.
J
4.540
42,666
Gauthey, (Euvres, ii. 150.
English, soft ...... ;j
4.334
40,824
1
Banks, Greg. Mech. i. 148. Ex. Hi.
* This is the mean result of thirty-three experiments.
f Kirwan, Elem. Miner, ii. 155.
J Calculated from experiments on the transverse strength, by arts. 14 and 15.
| Yielding to the file without difficulty.
205
TABLES OF THE COHESIVE FORCE OF SOLID BODIES.
TABLE I. — Continued.
METALS.
Specific cohe-
sion. Glass I.
"S-gc
«.S o
n
o cs.2
S.£
°G *>
&e
OQ 60
Hardness.
AUTHORITY.
CAST-IRON.
4.000
37,680
Rondelet, L'Art. de Batir, iv. 514.
Gray, of Cruzot, 2d fu-
sion *
3.257
30,680
Ramus, Gauthey, ii. 150.
Gray, of Cruzot, 1st fu-
sion *
COPPER.
Wire
3.202
6.606
30,162
61,228
Idem.f
Sickingen, Ann. de Chitnie, xxv. 9.
2 396
22,570
8.182
Muschenb. Intr ad Phil. Nat. i. 41 7.
PLATINDM.
Wire
2.152
5.995
20,272
56,473
8.726
20.847
8}
Idem.
MorveaUj Ann. de Chimie, xxv. 8.
Wire
5.625
52,987
S3
Sickingen, Ann. de Chimie, xxv. 9.
SILVER,
Wire
4.090
38.257
Sickingen, Ann. de Chimie, xxv. 9.
Cast... ,
4.342
40,902
11.091
73
Muschenb. Intr. ad Phil. Nat. i.417.
GOLD.
Wire
3279
30,888
Sickingen, Ann. de Chimie, xxv. 9.
Cast
2.171
20,450
19.238
fi!
Muschenb. Intr. ad Phil. Nat. i. 417.
TIN.
Wire
0.7568
7,129
1
Morveau, Ann. de China. Ixxi. 194.
Cast, English black
0.706
0.565
6,650
5,322
7.295 }•
fit
Muschenb. Intr. ad Phil. Nat. i. 417.
Idem.
— — lianca . ..
0 3906
3 679
7 2165 |
0 342
3 211
6 1256 J
BISMUTH.
Cast
0.345
3,250
9.810 )
•»•)
Muschenb. Intr, ad Phil. Nat.i 417
0.3193
3,008
9.926 J
'V
Idem. i. 454.
ZINC.
Wire
2 394
22 551
T
1.762
16,616
1
Cast. Goslar, from.
0 3118
2 937
«t
By my trial.
to
LEAD.
Milled
0.2855
0.3533
2,689
3,328
7.215 J
11 407")
Muschenb. Int. ad Phil. Nat. i. 417.
By my trial
Wire
0 334
3 146
11 348 1
Muschenb Intr ad Phil Nat i 452
Wire
0.274
2,581
11 282 j-
^>
Wire
0 2704
2 547
|
"I
Morveau Ann de Chim Ixxi 194
Cast, English
0.094
885
11 479 J
Muschenb Intr ad Phil. Nat i 452
0.1126
1 060
4 500
«-f
Muschenb Intr ad Phil Nat i 417
u +
* Calculated from experiments on the transverse strength, by arts. 14 and 15.
f In the operation of casting, the surface of the iron always becomes much harder, and
is more tenacious than the internal parts ; hence the strength of a small specimen is always
greater than that of a large one.
N. B. — When the specific gravity is not referred to a separate authority, it is to be con-
iidered that of the specimen of which the cohesive force is iriven.
J Kirwan's Miner, vol. ii. g Thomson's Chemistry, vol. L
206
TABLES OF THE COHESIVE FORCE OF SOLID BODIES.
TABLE II. — ALLOTS.
ALLO
Y OP
Specific cohe-
sion. Glass I.
HI
Hi
5£
'5 '£
8,2
co to
AUTHORITY.
Parts.
Gold 2
Gold 5
Silver 5
Parts.
Silver 1
Copper 1
Copper 1
2.972
5.307
6.148
28,000
50,000
48 500
Musch. Encyclop. Brit. art.
Idem. [Strength.
Idem.
Silver 4
Brass
Tin 1
4.352
4.870
41,000
45,882
Idem.
Muschenb., Colson, i. 242.
Copper 10
Tin 1
3.407
32,093
Musch. Intr. ad Phil Nat
Copper • 8
Tin 1
3.831
36,088
Idem. [i 428
Copper 6
Tin 1
4.687
44,071
Idem.
Copper 4
Tin 1
3.794
35 739
Idem.
Copper 2
Tin 1
0.108
1,017
Idem.
Tin 1
0 077
725
Tin English 10
Lead .. I
0 733
6 904
Musch Intr ad Phil ''Vat
Tin, 8
Tin, 6
Lead 1
Lead 1
0.841
0 849
7,922
7,997
Idem. [i. 438.
Idem.
Tin, 4
Tin, 2
Lead 1
Lead 1
1.126
0.793
10,607
7,470
Idem.
Idem.
Tin, 1
Tin, Banca 10
Tin, 8
i Tin, 6
Tin, 4
Tin, 2
Tin, 1
Tin, 10
Tin, 4
Tin, 2
Tin, 1
Tin, I
Tin, 1
Tin, 1
Tin, 10
Tin °
Lead 1
Antimony... 1
Antimony... 1
Antimony... 1
Antimony... 1
Antimony... 1
Antimony... 1
Bismuth 1
Bismuth 1
Bismuth 1
Bismuth 1
Bismuth 2
Bismuth 4
Bismuth 10
Zinc, Indian 1
Zinc 1
0.751
1.187
1.049
1.341
1.431
1.277
0.338
1.347
1.772
1.488
1.276
1.063
0.836
0.411
1.371
1 595
7,074
11,181
9,881
12,632
13,480
12,029
3,184
12,688
16,692
14,017
12,020
10,013
7,875
3,871
12,914
15 025
7.359
7.276
7.228
7.192
7.105
7.060
7.576
7.613
8.076
8.146
8.58
9.009
9.439
7.288
7 000
Idem.
Musch. Intr. ad Phil. Nat.
Idem. [i. 442.
Idem.
Idem.
Idem.
Idem.
Museh. Intr. ad Phil. Nat.
Idem. [i. 443.
Idem.
Idem.
Idem.
Idem.
Idem.
Musch. Intr. ad Phil. Nat,
Idem [i 444
Tin, 1
Zinc 1
1.682
15,844
7.321
Idem.
Tin 1
Zinc 2
I 701
16 023
7 100
Tin, 1
Zinc. 10
0 602
5 671
7 130
Idem
Tin. English 1
Tin, 2
Tin, 4
Zinc, Goslar 1
Zinc 1
Zinc 1
0.958
1.164
1.089
9,024
1<|,964
10,258
Musch. Intr. ad Phil. Nat.
Idem. [i. 446.
Idem.
Tin, 8
Zinc 1
1 126
10 607
Tin, 1
Tin. 3
Tin, 4
Lead, Scotch 1
Lead, 2
Lead, 10
Antimony... 1
Antimony... 2
Antimony... 1
Bismuth 1
Bismuth 1
Bismuth 1
0.154
0.338
1.202
0.777
0.620
0.300
1,450
3", 184
11,323
7,319
5,840
2,826
7.000
10. 31
11.090
10.827
Musch. Intr. ad Phil. Nat.
Idowu [i. 448.
Idem.
Musch. Intr. ad Phil. Nat,
Idem. [i. 454.
Idem.
207
TABULAR VIEW OF StfME OP THE PROPERTIES OF METALa
1
Specific
gravity.
Platinum 20.98
Gold 19.258
Iridium 18.680
Tungsten 17.50
Mercury 13.568
Palladium 1 1.50
Lead 11.35
Rhodium 11.0
Silver 10.47
Bismuth 9.80
Uranium 9.HO
Copper 8.89
Cadmium 8.60
Cobalt 8.53
Nickel 8.27
Iron 7.78
Molybdenum 7.40
Tin". 7.30
Zinc 7.00
Manganese 6.85
Antimony 6.70
Tellurium 6.10
Arsenic 5.8
Titanium 5.3
Sodium 0.972
Potassium 0.865
Chemical
equiva-
lents.
98.8
199.2
98.8
99.7
202.
53.3
103.6
52.2
108.
71.
217.
31.6
55.8
29.5
29.5
28.
47.7
57.9
32.3
27.7
64.6
64.2
37.7
24.3
23.3
39.15
ALLOYS possessed of greater specific gra-
vity than the mean of their components.
Gold and Zinc.
— Tin.
— Bismuth.
— Antimony.
— Cobalt.
Silver and Zinc.
— Lead.
— Tin.
— Bismuth.
— Antimony.
Copper and Zinc.
— Tin.
— Palladium.
— Bismuth.
— Antimony.
Lead and Bismuth.
— Antimony.
Platinum and Molybdenum.
Palladium and Bismuth.
FUSIBILITY.
Fahrenheit.
Mercury 39 deg.
Potassium 136
Sodium 190
Tin 442
Bismuth 497
Lead 612
Tellurium, rather less fusi-
ble than lead.
Arsenic, undetermined.
Zinc 773
Antimony, a little below a
red heat.
Cadmium, about 442
Silver 1873 deg.
/Copper 1996 "
/Gold 2016 "
j Cobalt, rather less fusible
than iron.
•g I Iron, cast 2786
C3 1 ,..it
I pttug™^ ^ smith,s forge>
e8 /Nickel, nearly the same as Cobalt.
£ /Palladium
-2 ^Molybdenum....
Uranium
Tungsten
Chromium
Titanium
Cerium
Osmium
Iridium
Rhodium
^Platinum
Columbium
Almost infusible and
not to be procured
in buttons by the
heat of a smith's
forge, but fusible
before the oxyhy-
drogen blowpipe.
ALLOYS having a specific gravity inferior
to the mean of their components.
Gold and Silver.
— Iron.
— Lead.
— Copper.
— Iridium.
— Nickel.
Silver and Copper.
Copper and Lead.
Iron and Bismuth.
— Antimony.
— Lead.
Tin and Lead.
— Palladium.
— Antimony.
Nickel and Arsenic.
Zinc and Antimony.
208
TABULAR VIEW OF METALS— Continued.
A
I
Titanium 1
Manganese _
Platinum V
Palladium
IARDNESS.
Harder than Steel.
Scratched by Calcspar.
Scratch glass.
Scratched by glass.
Scratched by the nail.
Liquid.
LITTLENESS.
metals are brittle, and
may even be reduced to
Manganese.
Molybdenum.
Rhodium.
Tellurium.
Titanium.
Tungsten.
Uranium.
MALLEABILITY,
Or admit of being extended by the
hammer.
Gold. Zinc.
Silver. Iron.
Copper. Nickel.
Tin. Palladium.
Cadmium. Potassium.
Platinum. Sodium.
Lead. Frozen Mercury.
ntJCTILITY,
Or admit of being drawn into wires.
Gold. Tin.
Silver. Lead.
Platinum. Nickel.
Iron. Palladium
Copper. Cadmium.
Zinc.
TENACITY.
Weights sustained by wires 0.787 of a
line diameter.
Trnn "i.lQ \}>* 9^0 dpf* Tit*
Gold
Silver. V
Tellurium
Bismuth
Cadmium
Nickel
Cobalt.
Antimony .
Zinc
Lead
Potassium
Mercury
BF
The following
most of them
powder.
Antimony.
Arsenic.
Bismuth.
Cerium.
Chromium.
Cobalt.
Colutnbium.
Copper 302 278 "
Platinum • . 274 320
Silver. 187 137
Gold 150 753
Zinc 109 540
Tin 34 " 630
Lead 27 " 621
Elasticity and sonorousness belong to the
hardest metals only, and are most evident
in certain alloys.
Odor and taste are most remarkable in
copper, iron, and tin.
LINEAR DILATATIONS BY HE;
Dimensions which a bar takes at 212°, who
at 32° is 1.000000; also its dilatation
fractions.
Platinum 1.00091085 or one 10
Palladium 1.00100000 " 10
^T.
se length
in vulgar
)7th part.
10th "
23d "
)lst "
24th "
)lst "
18th "
57th "
)7th "
50th »
24th '
17th '
J9th '
24th «
iOth «
36th "
le various
tionary of
POWER OF CONDUCTING
HEAT.
From Detpretz's Experiments.*
Conducting power.
Gold 100
1.00108300 " 9
Silver 97 3
Cast iron
1.00111025 " 9(
1.00121286 « 8'
1.00124860 « 8(
1.00139200 « 7
1.00149824 " 6
Iron 37 41
Wrought Iron....
Bismuth
Gold
Tin 30.38
Lead 17 96
.. 1.00179633 " 5.
MarVilft 2 34.
Gun metal (C.8,T.l) 1.00181700 " 5
Brass 1.00190663 " 5
Rriolr p-irfh 1 TS +
Speculum metal.
Silver
1.00193300 " 5
1 00200183 " 4
Tin
1.00235840 " 4
.. 1.00285768 " 3
* Ann. de Chim. et de Phys.
xix. 97.
f Trnite" EI6mentairede Phy-
sique, par M. Despretz, p. 20, as
quoted by,Dr. Thomson, on Heat
and Electricity, p. 103.
Lead
Zinc 1.00297650 " 3
The above are the mean proportions of tl
examples of each metal, given in Ure'a Die
Chemistry and elsewhere.
I
209
WEIGHTS OF WROUGHT-IRON, STEEL, COPPER, AND BRASS WIRE
AND PLATES.
The specific gravities to determine the weights of the following-
named metals, and the calculations of them, were taken and made
by Charles H. Haswell, of New York, for the well-known manu-
facturers, Messrs. J. K. Brown & Sbarpe, of Providence, R. 1.
Diameter and thickness determined by American gage : —
No. of
Gage.
Size of
each
number.
WIRE— PER LINEAL FOOT.
PLATES— PER LINEAL FOOT.
Wrought
Iron.
St-el.
Copper.
Bra«.
Wrought
Iron.
Steel.
Copper. | Vasa.
!
Inch.
Lbs.
Lbs.
Lbs.
Lbs.
Lb».
Lbs.
Lbs.
Lbs. |
0000
.46000
.560740
.566030
.640513
.605176
17.25
17.48
20.838
19.688
000
.40964
.444683
.448879
.507946
.479908
16.3616
15.5663
18.6567
17.5326
00
.36480
.352659
.355985
.402830
.380666
13.68
13.8624
16.5254
15.6134
0
.32486
.279665
.282303
.319451
.301816
12.1823
12.3447
14.7162
13.904
1
.28930
.221789
.223891
.253342
.239353
10.8488
10.9934
13.1063
12.382
2
.25763
.175888
.177548
.200911
.189818
9.6611
9.7899
11.6706
11.0266
3
.2-2942
.139480
.140796
.159323
.150622
8.6033
8.7180
10.3927
9.8192
4
.20431
.110616
.111660
.126363
.119376
7.6616
7.7638
9.2552
8.7445
5
.18194
.087720
.088548
.100200
.094666
6.8228
6.9137
8.2419
7.787
6
.16202
.069565
.070221
.079462
.075075
6.0768
6.1568
7.3395
6.9345
7
.14428
.055165
.055685
.063013
.059545
5.4105
6.4826
6.6359
6.1752
8
.12849
.043751
.044164
.049976
.047219
4.8184
4.8826
5.8206
5.4994
9
.11443
.034699
.035026
.039636
.037437
4.2911
4.3483
6.1837
4.8976
10
.10189
.027512
.027772
.031426 .
.029687
3.8209
3.8718
4.6156
4.3609
11
.090742
.021820
.022026
.024924
.023549
3.4028
3.4482
4.1106
3.8838
12
.080808
.017304
.017468
.019766
.018676
3.0303
3.0707
3.6606
3.4586
13
.071961
.013722
.013861
.015674
.014809
2.6985
2.7345
3.2598
3.0799
14
.064084
.010886
.010909
.012435
.011746
2.4032
2.4352
2.9030
2.7428
15
.057068
.008631
.008712
.009859
.009315
2.1401
2.1686
2.6852
2.4425
16
.050320
.006845
.006909
.007819
.007587
.9058
1.9312
2.3021
2.1751
17
.045257
.005407
.005478
.006199
.006857
.6971
1.7198
2.0501
1.937
18
.040303
.004304
.004304
.004916
.004645
.5114
1.6315
1.8257
1.726
19
.035890
.003413
.003446
.003899
.003684
.34)9
1.3638
1.6258
1.636*
20
.031961
.002708
.002734
.003094
.002920
.1985
1.2145
1.4478
1.3679
21
.028462
.002147
.002167
.002452
.002317
.0673
1.0816
1.2893
1.2182
22
.025347
.001703
.001719
.001945
.001838
.95051
.96319
1.1482
1.0849
23
.022571
.001350
.001363
.001542
.001457
.84641
.8577
1.0225
.96604
24
.020100
.001071
.001081
.001223
.001155
.75375
.7638
.91053
.86028
25
.017900
.0008491
.0008571
.0009699
.0009163
.67126
.6802
.81087
.76612
26
.015940
.0006734
.0006797
.0007692
.0007267
.69775
.60572
.72208
.68223
27
.014195
.0005340
.0005391
.0006099
.0005763
.63231
.53941
.64303
.60755
28
.012641
.0004235
.0004275
.0004837
.0004570
.47404
.48036
.67264
.63103
29
.011257
.0003358
.0003389
.0003836
.0003624
.42214
.42777
.60994
.48180
30
.010025
.0002663
.0002688
.0003042
.0002874
.37594
.38096
.46413
.42907
31
.008928
.0002113
.0002132
.0002413
.0002280
.3348
.33926
.40444
.38212
32
.007950
.0001675
.0001691
.0001913
.0001808
.29813
.3021
.36014
.34026
33
.007080
.0001328
.0001341
.0001517
.0001434
.2655
.26904
.32072
.30302
34
.006804
.0001053
.0001065
.0001204
.0001137
.2364
.23966
.28557
.26981
35
.005614
.00008366
.00008445
.0000956
.00009015
.21053
.21333
.25431
.24028
36
.005000
.00006625
.00006687
.0000757
.0000716
.1875
.19
.2265
.2140
37
.004453
.00005255
.00005304
.00006003
.00005671
.16699
.16921
.20172
.19059
38
.003965
.00004166
.00005206
.00004758
.00004496
.14869
.16067
.17961
.1697
39
.003531
.00003305
.00003336
.00003775
.00003566
.13241
.13418
.16995
.15113
40
.003144
.00002320
.00002644
.00002992
.00002827
.1179
.11947
.14242
.13456
Specific, Gravities .. 7.774 7^
8.880
8.386 II 7.200 7.2% 8.698 8.218
WeigMs of a cub. ft. 585.87 490.45
554.988
624.16 460. 466. 643.6 613.6
14
210 THE PRACTICAL METAL- WORKER'S ASSISTANT.
CHAPTER XIII.
REMARKS ON THE CHARACTERS OF THE METALS AND ALLOYS.
HARDNESS, FRACTURE, AND COLOR OF ALLOYS. — The object of
the present chapter is to explain in a general way some of the pe-
culiarities and differences amongst alloys, prior to entering on the
means of melting the metals, without which process alloys cannot
be made : yet notwithstanding that the list contains the greater
number of the alloys in ordinary use, and many others, it is merely
a small fraction of those which might be made.
It is also stated that metals appear to unite with one another in
every proportion, precisely in the same manner as sulphuric acid
and water. Thus there is no limit to the number of alloys of gold
and copper. The same might be said of many other metals, and
when the alloys compounded of three, four, or more metals, are
taken into account, the conceivable number of alloys becomes almost
unlimited. It is certain, however, that metals have a tendency to
combine in definite proportion ; for several atomic compounds of
this kind occur native. It is indeed possible that the variety of
proportions in alloys is rather apparent than real, arising from the
mixture of a few definite compounds with each other, or with un-
combined metal ; an opinion not. only suggested by the mode in
which alloys are prepared, but in some measure supported by
observation.
It appears to be scarcely possible to give any sufficiently general
rules, by which the properties of alloys may be safely inferred from
those of their constituents ; for although, in many cases, the work-
ing qualities and appearance of an alloy, may be nearly a mean
proportional between the nature and quantities of the metals com-
posing it ; yet in other and frequent instances the deviations are
excessive, as will be seen by several of the examples referred to.
Thus, when lead, a soft and malleable metal, is combined with
antimony, which is hard, brittle, and crystalline, in the proportions
of from twelve to fifty parts of lead to one of antimony ; a flexible
alloy is obtained, resembling lead, but somewhat harder, and which
is rolled into sheets for sheathing ships. Six parts of lead and one
of antimony are used for the large soft printers' types, which will
bend slightly, but are considerably harder than the foregoing ; and
three parts of lead and one of antimony are employed for the small-
est types, that are very hard and brittle, and will not bend at all ;
antimony being the more expensive metal, is used in the smallest
quantity that will suffice.
In this alloy the antimony fulfills another service besides that of
.mparting hardness: antimony somewhat expands on cooling,
CHARACTERS OF METALS AND ALLOYS. 211
whereas lead contracts very much, and the antimony, therefore,
within certain limits, compensates for this contraction, and causes
the alloy to retain the full size of the moulds.
Sometimes, from motives of economy, the neighboring parts of
machinery are not wrought accurately to correspond one with the
other, bat lead is poured in to fill up the intermediate space, and
to make contact ; as around the brass nuts in the heads of some
screw presses, in the guides or followers for the same, and some
other parts of either temporary or permanent machinery. Anti-
mony is quite essential in all these cases to prevent the contraction
the lead alone would sustain, and which would defeat the intended
object, as the metal would otherwise become smaller than the space
to be filled.
A little tin is commonly introduced into types, and likewise cop-
per in minute quantity; iron and bismuth are also spoken of; the
last is said to be employed on account of its well -Known property
of expanding in cooling, so as to cause the types to swell in the
mould, and copy the face of the letter more perfectly, but although
I find bismuth to have been thus used it appears to be neither
common nor essential in printing-types.
The difference in specific gravity between lead and antimony
constantly interferes, and unless the type metal is frequently stirred,
the lead, from being the heavier metal, sinks to the bottom, and the
antimony is disproportionally used from the surface.
In the above examples, the differences arising from the propor-
tions appear intelligible enough, as when the soft lead prevails, the
mixture is much like the lead ; and as the hard, brittle antimony is
increased, the alloy becomes hardened, and more brittle : with the
proportion of four to one, the fracture is neither reluctant like that
of lead, nor foliated like antimony, but assumes very nearly the
grain and color of some kinds of steel and cast-iron. In like man-
ner, when tin and lead are alloyed, the former metal imparts to the
mixture some of its hardness, whiteness, and fusibility, in propor-
tion to its quantity ; as seen in the various qualities of pewter, in
which however copper, and sometimes zinc or antimony are found.
The same agreement is not always met with ; as nine parts of
copper, which is red, and one part of tin, which is white, each very
malleable and ductile metals, make the tough, rigid metal used in
brass ordnance, from which it obtains its modern name of gun-
metal, but which neither admits of rolling nor drawing into wire ;
the same alloy is described by Pliny as the soft bronze of his day.
The continual addition of the tin, the softer metal, produces a
gradual increase of hardness in the mixture ; with about one-sixth
of tin the alloy assumes its maximum hardness consistent with it?
application to mechanical uses ; with one-fourth to one- third tin it
becomes highly elastic and sonorous, and its brittleness rather than
its hardness is greatly increased.
When the copper becomes two, and the tin one part, the alloy is
so hard as not to admit of being cut with steel tools, but crumbles
212 THE PRACTICAL METAL-WORKER'S ASSISTANT.
under their action ; when struck with a hammer or even suddenly
warmed it flies in pieces like glass, and clearly shows a structure
highly crystalline, instead of malleable. The alloy has no trace of
the red color of the copper, but it is quite white, susceptible of an
exquisite polish, and being little disposed to tarnish, it is most per-
fectly adapted to the reflecting speculums of telescopes and other
instruments, for which purpose it is alone used.
Copper, when combined in the same proportions with a different
metal, also light-colored and fusible, namely, two parts of copper,
with one of zinc, (which latter metal is of a bluish-white, and crys-
talline, whereas tin is very ductile,) makes an alloy of entirely oppo-
site character to the speculum metal ; namely, the soft; yellow brass,
which becomes by hammering very elastic and ductile, and is very
easily cut and filed.
Again, the same proportions, namely, two parts of copper and
one of lead, make a common inferior metal, called pot-metal, or
cock-metal, from its employment in those respective articles. This
alloy is much softer than brass, and hardly possesses malleability ;
when, for example, the beer- tap is driven into the cask, immediately
after it has* been scalded, the blow occasionally breaks it in pieces,
from its reduced cohesion.
Another proof of the inferior attachment of the copper and lead
exists in the fact that, if the moulds are opened before the castings
are almost cold enough to be handled, the lead will ooze out and
appear on the surface in globules. This also occurs to a less extent
in gun-metal, which should not on that account be too rapidly ex-
posed to the air ; or the tin strikes to the surface, as it is called, and
makes it particularly hard at those parts, from the proportional in-
crease of the tin. In casting large masses of gun-metal, it frequently
happens that little hard lumps, consisting of nearly half tin, work'
up to the surface of the runners or pouring places, during the time
the metal is cooling.
In brass, this separation scarcely happens, and these moulds may
be opened whilst the castings are red hot, without such occurrence ;
from which it appears that the copper and zinc are in more perfect
chemical union than the alloys of copper with tin and with lead.
MALLEABILITY AND DUCTILITY OF ALLOYS. — The malleability
and ductility of alloys are in a great measure referable to the de-
grees in which the metals of which they are respectively composed,
possess these characters.
Lead and tin are malleable, flexible, ductile, and inelastic whilst
cold, but when their temperatures much exceed about half way to-
wards their melting heats they are exceedingly brittle and tender
owing to their reduced cohesion.
The alloys of lead and tin partake of the general nature of these
two metals; they are flexible when cold, even with certain addi-
tions of the brittle metals, antimony and bismuth, or of the fluid
metal mercury ; but they crumble with a small elevation of tempera-
ture; as these alloys melt at a lower degree than either of their
CHARACTERS OF METALS AND ALLOYS. 213
components, to which circumstance we are indebted for the tin
solders.
Zinc, when cast in thin cakes, is somewhat brittle when cold, but
its toughness is so far increased when it is raised to about 300° F.
that its manufacture into sheets by means^ of rollers is then admissi-
ble ; it becomes the malleable zinc, and "retains the malleable and
ductile character, in a moderate degree, even when cold, but in
bending rather thick plates it is advisable to warm them to avoid
fracture ; when zinc is remelted, it resumes its original crystalline
condition. It is considered that most of the sheet zinc contains a
very little lead.
Zinc and lead will not combine without the assistance of arsenic,
unless the lead is in very small quantity. The arsenic makes this
and other alloys very brittle, and it is besides dangerous to use.
Zinc and tin make, as may be supposed, somewhat hard and brittle
alloys, but none of the zinc alloys, except that with copper to con-
stitute brass, are much used.
Gold, silver, and copper, which are greatly superior in strength
to the fusible metals above named, may be forged either when red-
hot or cold, as soon as they have been purified from their earthy
matters, and fused into ingots ; and the alloys of gold, silver, and
copper, are also malleable, either red-hot or cold.
Fine, or pure gold and silver, are but little used alone. The
alloy is in many cases introduced less with the view of depreciating
their value than of adding to their hardness, tenacity, and duc-
tility. The processes which the most severely test these qualities,
namely, drawing the finest wires, and beating gold and silver leaf,
are not performed with the pure metals, but gold is alloyed with
copper for the red tint, with silver for the green, and with both for
intermediate shades. Silver is alloyed with copper only, and when
the quantity is small its color suffers but slightly from the addition,
although its working qualities are greatly improved, pure silver
being little used.
The alloys of similar metals having been considered, it only re-
mains to observe that when dissimilar metals are combined, as
those of the two opposite groups ; namely, the fusible lead, tin, or
zinc, with the less fusible copper, gold, and silver, the malleability
of the alloys when cold is less than that of the superior metal ;
and when heated barely to redness, they fly in pieces under the
hammer ; and, therefore, brass, gun-metal, etc., when red-hot, must
be treated with precaution and tenderness. It will be remembered
the action of rollers is more regular than that of the hammer, and
soon gives rise to the fibrous character, which, so far as it exists
in metals, is the very element of strength when it is uniformly
distributed throughout their substance. This will be seen by the
inspection of the relative degrees of cohesion possessed by the same
metal when in the conditions of the casting, sheet, or wire, shown
by the table, and to which quality or the tenacity of the alloys we
shall now devote a few lines.
214 THE PRACTICAL METAL-WORKER'S ASSISTANT.
STRENGTH OR COHESION OF ALLOYS. — The strength or cohesion
of the alloys is in general greatly superior to that of any of the
metals of which they are composed. For example, on comparing
some of the numbers of the table on pages 206 and 208, it will be
seen that the relative weights, which tear asunder a bar one inch
square of the several substances, stand as follows, — all the num-
bers being selected from Muschenbroek's valuable investigations,
so that it may be presumed the same metals; and also the same
means of trial, were used in every case.
Allovs. Cast Metals.
10 Copper, 1 Tin, 32,093 Ibs.
8 _ — 36,088 "
- 44,071 "
- 35,739 "
Barbary Copper, 22,570 Ibs.
Japan — 20,272 "
English Block Tin, 6,650
Do. 5,322
Banca Tin, 3,679
Malacca Tin, 3,211
4 —
2 — — 1,017
1 _ _ 725 •' I
The inspection of these numbers is highly conclusive, and it
shows that the engineer agrees with theory and experiment in
selecting the proportion 6 to 1 as the strongest alloy ; and that the
philosopher, in choosing the most reflective mixture, employs the
weakest but one, — its strength being only one-third to one-sixth
that of the tin, or one-twentieth that of the copper, which latter
constitutes two-thirds its amount.
It is much to be regretted that the valuable labors of Muschen-
broe'k have not been followed up by other experiments upon the
alloys in more general use. One curious circumstance will be ob-
served, however, in those which are given, namely, that in the
following alloys, which are the strongest of their respective groups,
the tin is always four times the quantity of the other metal ; and
they all confirm the circumstance of the alloys having mostly a
greater degree of cohesion than the stronger of their component
metals.
Alloys. Cast Metals.
4 English Tin, 1 Lead, 10,607 Ibs.
4 Banca Tin, 1 Antimony, 13.480 "
4 — — 1 Bismuth, 16,692 "
4 English Tin, 1 Goslar Zinc, 10,258
Lead, 885 Ibs.
Antimony, 1,060 "
Zinc, 2,689 "
Bismuth, 3,008 "
Tin, 3,211 to 6,650 "
4 — — 1 Antimony, 11,323 '
Fig. 118 represents a very ingenious instrument, denominated an
alloy-balance. It is intended for weighing those metals the propor-
tions of which are stated decimally: its principle, which is so simple
as hardly to require explanation, depends upon the law that weights
in equilibrium are inversely as their distances from the point of
support.
For weighing out any precise number of pounds or ounces, in
the common way, the arms of the ordinary scale-beam are made as
* This, in truth, is an exception ; it barely equals in strength the alloys
with 8 and 2 parts of tin to 1 of zinc, but is superior to that of equal parts.
It corroborates the great increase of strength in alloys generally.
CHARACTERS OF METALS AND ALLOYS.
215
nearly equal as possible ; so that the weights, and the articles to be
weighed, maybe made to change places, in proof of the equality of the
Fig. 118.
instrument. But to weigh out an alloy, say of 17 parts tin and 83
copper, unless the quantities were either 17 and 83 Ibs. or ounces,
would require a little calculation.
This is obviated, if the point of suspension a, of the alloy -balance,
which is hung from any fixed support b, is adjusted until the arms
are respectively as 17 to 83 ; and for this purpose the half of the
beam is divided into fifty equal parts numbered from the one end;
and, prior to use, it only remains to adjust the weight, w? so as to
place the empty balance in equilibrium. A quantity of copper,
rudely estimated, having been suspended from the short arm of the
balance, the proportionate quantity of the tin will be denoted with
critical accuracy, when, by its gradual addition, the beam is exactly
restored to the horizontal line ; should the alloy consist of three or
more parts, the process of weighing is somewhat more complex.
The annexed table was calculated by the author, for converting the
proportions of alloys stated decimally, into avoirdupois weight. It
applies with equal facility to alloys containing two or many compo-
nents, so as to bring them readily within the power of ordinary scale?
216
THE PRACTICAL METAL-WORKER'S ASSISTANT.
TABLE FOR CONVERTING DECIMAL PROPORTIONS
Into Divisions of the Pound Avoirdupois.
Decimal.
oz. dr.
Decimal, joz. dr.
Decimal.
oz. dr.
Decimal.
oz. dr.
1
.78
1
13.28
2 1
25.78
4 1
38.28
6 1
1.56
2
14.06
2 2
26.56
4 2
39.06
6 2
2.34
3
14.84
2 3
27.34
4 3
39.84
6 3
3.12
4
15.62
2 4
28.12
4 4
40.62
6 4
3.91
5
16.4 L
2 5
28.91
4 5
41.41
6 5
4.69
6
17.19
2 6
29.69
4 6
42.19
6 6
5.47
7
17.97
2 7
30.47
4 7
42.97
6 7
6.25
1 0
18.75
3 0
31.25
5 0
43.75
7 0
7.03
1 1
19.53
3 1
32.03
5 1
44.53
7 1
7.81
1 2
20.31
3 2
32.81
5 2
45.31
7 2
8.59
1 3
21.09
3 3
33.59
5 3
46.09
7 3
9.37
1 4
21.87
3 4
34.37
5 4
46.87
7 4
10.16
1 5
22.66
3 5
35.16
5 5
47.66
7 5
10.94
1 6
23.44
3 6
35.94
5 6
48.44
7 6
11.72
1 7
24.22
3 7
36.72
5 7
49.22
7 7
12.50
2 0
25.06
4 0
37.50
6 0
50.00
8 0
Application of the Table.
The Chinese Packfong, similar to our German silver, is said to
consist of —
40.4 parts of Copper ~) f 6 oz. 4 drams, nearly.
t to
2.6 — Iron
100.0 parts
[ 0 — 3 — full.
16 oz. 0 — Avoird's.
All nice attempts at proportion are, however, entirely futile, un-
less the metals are perfectly pure; for example, it is a matter of
common observation that for speculums a variable quantity of from
seven and a half to eight and a half ounces of tin is required for
the exact saturation of every pound of copper, and upon which
saturation the efficiency of the compound depends ; bells of exactly
similar quality sometimes thus require the dose of tin to vary from
three and a half to five ounces to the pound of copper, according
to the qualities of the metals.
The variations in the purity of the metals obtained from different
localities are abundantly demonstrated by the disagreement in the
cohesive strengths of the two in question, more particularly the tin,
as seen on page 214, and which can be only ascribed to their re-
spective amounts of impurity. Any other supposition than the
CHARACTERS OF METALS AXD ALLOYS. 217
presence of foreign matter, would necessarily go to disprove the
fact of the metals being simple bodies, and therefore strictly alike
when absolutely pure, .wheresoever they may have been obtained.
FUSIBILITY OF ALLOYS. — In concluding this slight view of some
of the general characters of alloys, it remains to consider the influ-
ence of heat, both as an agent in their formation and as regards
the degree in which it is required for their after- fusion ; the lowest
available temperature bein^ the most desirable in every such case.
Metals do not combine with each other in their solid state, owing
to the influence of chemical affinity being counteracted by the
force of cohesion. It is necessary to liquefy at least one of them,
in which case they always unite, provided their mutual attraction is
energetic. Thus, brass is formed when pieces of copper are put
into melted zinc ; and gold unites with mercury at common tem-
peratures by mere contact.
The agency of mercury in bringing about triple combinations of
the metals, both with and without heat, is also very curious ana
extensive. Thus, in water- gilding, the silver, copper, or gilding
metal, when chemically clean, is rubbed over with an amalgam
of gold containing about eight parts of mercury ; this immediately
attaches itself, and it is only necessary to evaporate the mercury,
which requires a very moderate heat, and the gold is left behind.
Water-silvering is similarly accomplished.
Cast-iron, wrought-iron, and steel, as well as copper and many
other metals, may be tinned in a similar manner. An amalgam of
tin and mercury is made so as to be soft and just friable ; the metal
to be tinned is thoroughly cleaned, either by filing or turning, or
if only tarnished by exposure, it is cleaned with a piece of emery-
paper or otherwise, without oil, and then rubbed with a thick cloth
moistened with a few drops of muriatic acid. A little of the amal-
gam then rubbed on with the same rag, thoroughly coats the cleaned
parts of the metal by a process which is described as cold- tinning •
other pieces of metal may be attached to the tinned parts by the
ordinary process of tin- soldering.
In making the tinned iron plates, the scoured and cleaned iron
plates are immersed in a bath of pure melted tin, covered with pure
tallow, the tin then unites with every part of the surfaces ; and in
the ordinary practice of tinning culinary vessels of copper, pure tin
is also used. The two metals, however, must then be raised to the
melting heat of tin ; but the presence of a little mercury enables
the process to be executed at the atmospheric temperature, as above
explained.
In M. Mallet's recently patented processes for the protection of
iron from, oxidation and corrosion, and for the prevention of the
fouling of ships, one proceeding consists in covering the iron with
zinc.
The ribs or plates for iron ships are immersed in a cleansing bath
of equal parts of sulphuric or muriatic acid and water, used warm ;
the works are then hammered, and scrubbed with emery or sand.
218 THE PRACTICAL METAL-WORKER'S ASSISTANT.
to detach the scales and to thoroughly clean them; they arc then
immersed in a preparing bath of equal parts of saturated solutions
of muriate of zinc and sal-ammoniac, from which the works are
transferred to a fluid metallic bath, consisting of 202 parts of mer-
cury and 1292 parts of zinc, both by weight (being in the proportion
of one atom of mercury to forty atoms of zinc) ; to every ton weight
of which alloy, is added about one pound of either potassium or
sodium (the metallic bases of potash and soda), the latter being
preferred. As soon as the cleaned iron works have attained the
melting heat of the triple alloy, they are removed, having become
thoroughly coated with zinc.
The affinity of this alloy for iron is, however, so intense, and the
peculiar circumstances of surface as induced upon the iron presented
to it by the preparing bath are such, that care is requisite least
by too long an immersion the plates are not partially or wholly
dissolved. Indeed where the articles to be covered are small, or
their parts minute, such as wire, nails or small chain, it is necessary
before immersing them to permit the triple alloy to dissolve or
combine with some wrought-iron, in order that its affinity for iron
may be partially satisfied and thus diminished. At the proper
fusing temperature of this alloy, which is about 680° Fahr., it will
dissolve a plate of wrought-iron of an eighth of an inch thick in a
few seconds,
The Palladiumizing Process. — The articles to be protected are to
be first cleansed in the same way as in the case of zincing ; namely,
by means of the double salts of zinc and ammonia, or of manganese
and ammonia ; and then to be thinly coated over with palladium,
applied in a state of amalgam with mercury.
In the opinion of eminent chemists and metallurgists, all the met-
als, even the most refractory which nearly, or quite refuse to melt
in the crucible when alone, will gradually run down when sur-
rounded by some of the more fusible metals in the fluid state ; in a
manner similar to the solution of the metals in mercury, as in the
amalgams, or the solutions of solid salts in water. The surfaces of
the superior metals are, as it were, dissolved, washed down, or re-
duced to the state of alloys, layer by layer, until the entire mass is
liquefied.
Thus nickel, although it barely fuses alone, enters into the com-
position of German silver by aid of the copper, and whilst it gives
whiteness and hardness, it also renders the mixture less fusible.
Platinum combines very readily with zinc, arsenic, and also with
tin and other metals ; so much so that it is dangerous to melt either
of those metals in a platinum spoon ; or to solder platinum with
common tin solder, which fuses at a very low temperature : although
platinum is constantly soldered with fine gold, the melting point of
which is very high in the scale. Again, the circumstances that
some of the fusible bismuth alloys melt below tlie temperature of
boiling water, or at less than half the melting heat of tin, their most
fusible ingredient, show that the points of fusion of alloys are
CHARACTERS OF METALS AND ALLOYS. 219
equally as difficult of explanation or generalization as many other
of the "anomalous circumstances concerning them.
This much, however, may be safely advanced, that alloys, without
exception, are more easily fused than the superior metal of which
they are composed ; and extending the same view to the relative
quantities of the components, it may be observed that, the hard
solders for the various metals and alloys, are in general made of
the self-same material which they are intended to join, but with small
additions of the more fusible metals. The solder should be, as
nearly as practicable, equal to the metal on which it is employed,
in hardness, color, and every property except fusibility ; in which
it must excel just to an extent that, when ordinary care is used,
will avoid the risk of melting at the same time, both the object to
be soldered and likewise the softer alloy or solder by which it is
intended to unite its parts
It would appear as if every example of soldering in which a more
fusible alloy is interposed, were also one of superficial alloying.
Thus, when two pieces of iron are united by copper, used as a sol-
der, it seems to be a natural conclusion that each surface of the iron
becomes alloyed with the copper : and that the two alloyed surfaces
are held together from their particles having been fused in contact,
and run into one film. It is much the same when brass or spelter
solder is used, except that triple alloys are then formed at the sur-
faces of the iron, and so with most other instances of soldering.
And in cases where metallic surfaces are coated by other metals,
the latter being at the time in a state of fusion, as in tinned-iron
plates and silvered copper ; may it not also be conceived, that be-
tween the two exterior surfaces, which are doubtless the simple
metals, a thin film of an alloy compounded of the two does in reality
exist ? And in those cases in which the coating is laid on by the
aid of mercury, and without heat, the circumstances are very sim-
ilar, as the fluidity of mercury is identical with the ordinary state
of fusion of other metals, although the latter require higher tem-
peratures than that of our atmosphere.
When portions of the same metal are united by partial fusion,
and without solder, as in the process described as burning together,
and more recently known as the " autogenous" mode of soldering,
no alloy is formed, as the metals simply fuse together at then-
surfaces.
Neither can it be supposed that any formation of alloy can
occur, where the one metal is attached to the other by the act of
burnishing on with heat, as in making gilt wire, but without a
temperature sufficient to fuse either of the metals. The union in
this case is probably mechanical, and caused by the respective par-
ticles or crystals of the one metal being forced into the pores of
the other, and becoming attached by a species of entanglement,
similar to that which may be conceived to exist throughout solid
bodies. This process, almost more than any other in common use,
requires that the metals should be perfectly or chemically clean ;
220
for which purpose they are scraped quite bright before they are
burnished together, so that the junction may be next approaching
to that of solids generally.
And, lastly, when metals are deposited upon other metals by
chemical or electrical means, the addition frequently appears to be
a detached sheath, and which is easily removed ; indeed, unless the
metal to be coated is chemically clean, and that various attendant
circumstances are favorable, the sound and absolute union of the
two does not always happen, even when carefully aimed at.
It is time, however, that we proceed to the description of the
methods of forming the ordinary alloys, the subject of the succeed-
ing matter.
CHAPTEK XIY.
MELTING AND MIXING- THE METALS.
THE VARIOUS^FURNACES, ETC., FOE MELTING THE METALS. —
The subject upon which we have now to enter consists of two
principal divisions, namely, the melting and combining of the met-
als, and the formation of the moulds into which the fluid metals
are to be poured. In the foundry the two processes are generally
carried on together, so that by the time the mould is completed,
the metal may be ready to be poured into it ; but as in conveying
these several particulars the one process must have precedence, I
propose to commence with the means ordinarily employed in melt-
ing and mixing the metals, in order to associate more closely all
that concerns the alloys. In accordance with ordinary practice,
the formation of the moulds will be described whilst the metals
may be supposed to be in course of fusion ; the concluding re-
marks will be on pouring, or filling the moulds, the act strictly
speaking of casting, and which completes the work.
The fusible metals, or those not requiring the red-heat, are melted
when in small quantities in the ordinary plumber's ladle over the
fire ; otherwise larger cast-iron ladles or pans are used, beneath
which a fire is lighted ; for very large quantities and various manu-
facturing purposes, such as casting sheet-lead, and lead pipe, and
also for type-founding, the metals are melted in iron pans set in
brickwork, with a fire-place and ash-pit beneath, much the same as
an ordinary laundry copper, and the metals are removed from the
pans with ladles.
The pewterers and some others call the melting pan a pit.
although it is erected entirely above the floor ; and as their meltings
are made up in great part of old metal, which is sometimes wet or
damp; they have iron doors to enclose the mouth of the pan, in
MELTING AND MIXING THE METALS.
221
case any .of the metal should be splashed about from the moisture
reaching the fluid metal.
Antimony, copper, gold, silver, and their alloys, are for the most
part melted in crucibles within furnaces similar to the kind used
by the brass founders, which is represented at a, Fig. 119 ; the en-
tire figure represents the imaginary section of a brass foundry
with the moulding trough, b, for the sand on the side opposite the
furnace, the pouring or spill trough, c, in the centre, and the core
oven d, which is usually built in the wall close against one of the
flues ; but these matters will be described hereafter.
The brass furnace is usually built within a cast-iron cylinder,
about 20 to 24 inches diameter and 30 to 40 inches high, which is
erected over an ash-pit arrived at through a loose grating on a
loor of the foundry. The mouth of the furnace
Fig. 119.
level with the floor
stands about 8 or 10 inches above the floor, and its central aper
ture is closed with a plate now usually of iron, although still
called a tile ; the inside of the furnace is contracted to about 10
inches diameter by fire-bricks set in Stourbridge clay, except a
small aperture at the back about 4 or 5 inches square, leading into
the chimney.
There are generally three or four such furnaces standing in a row,
and separate flues proceed from all into the great chimney or stack,
the height of which varies from about twenty to forty feet, and up-
wards, the more lofty it is the greater the draught ; every furnace
has also a damper to regulate its individual fire.
It is quite essential for constant work to have several furnaces,
in order that one or two may be in use, whilst the others lie idle to
allow of their being repaired, as they rapidly burn away, and when
the space around the crucible exceeds about 2 or 3 inches, the fuel
is consumed unnecessarily quick ; the furnace is then contracted /to
its original size with a dressing of road drift and water applied
222
like mortar, the fire is lighted immediately, and urged vigorously
to glaze the lining. Koad drift, or the scrapings of the ordinary
turn-pike roads, principally silex and alumina, is often used for the
entire lining of the furnaces. The refuse sand from the glass
grinders, which contain flint glass, is also used for repairing them.
It is also convenient to have several furnaces for another reason,
as when a single casting requires more than the usual charge of one
furnace, namely, about 40 to 60 Ibs., two or more fires can be used.
When the quantity of brass to be melted exceeds the charge of
three or four ordinary air furnaces, the common blast furnace for
iron is sometimes used as a temporary expedient ; the practice,
however, is bad, as it causes great oxidation and waste. The
greatest quantities of metal, as for large bells, statues, and ordnance,
amounting sometimes to several tons, are commonly melted in re-
verberatory furnaces.
The furnaces used by the gold and silver refiners are in many
respects similar to the brass burnace a. Fig. 119, but they are built
as a stunted wall along one or more sides of the refinery, and en-
tirely above the floor of the same. The several apertures for the
fuel and crucible are from 9 to 16 inches square, or else cylindri-
cal, and 12 to 20 inches deep ; the front edge of the wall is horizon-
tal, and stands about 30 inches from the ground, but from the»
mouth of the furnace backwards it is inclined at an angle of about
20 to 40 degrees, so that the tiles, or the iron covers of the furnace,
lie at that angle. A narrow ledge cast in the solid with the iron
plates covering the upper surface of the wall, retains the tiles ID
their position.
The small kinds of air furnaces are of easy construction, but as a
temporary expedient almost any close fire may be used, including
some of the German stoves and hot-air stoves, that is for melting
brass, which is more fusible than copper ; although it is much the
most convenient that the fire be open at the top, so that the con-
tents of the crucible may be seen without the necessity for its re-
moval from the fire. Such stoves, however, radiate heat in a some-
what inconvenient manner, and to a much greater extent than the
various portable furnaces, most of which are lined with fire-brick
or clay ; the lining concentrates the heat and economizes the fuel.
Many of these portable furnaces answer not only for copper but
also for iron, when they have a good draft ; it may happen, however,
that the chemical furnaces are equally as inaccessible to the ama-
teur as those expressly constructed for the metals.
Country blacksmiths, who are frequently called upon to practice
many trades, sometimes melt from ten to fifteen pounds of brass in
the ordinary forge fire, but there is considerable risk of cracking
the earthen crucible at the point exposed to the blast ; a wrought-
iron pot is sometimes resorted to, but this is not very enduring, as
the brass will soon cause it to burn into holes and leak.
, OBSERVATIONS ON THE MANAGEMENT OF THE FURNACE, AND ON
MIXING ALLOYS. — The fuel for the brass furnace is always hard
MELTING AND MIXING THE METALS. 223
coke, which is prepared in ovens and broken into lumps about tho
size of hens' eggs : in lighting the fire, a bundle of shavings, chips,
of cork, or any similar combustible, is first thrown in and ignited,
and then some coke or charcoal is added. It is also usual to put
the pot in the fire at an early stage, and with its mouth down-
wards: by this means the thin edge which admits the most easily
of expansion gets hot first, and the heat plays within the crucible,
so as to warm it gradually : it is not reversed until the whole is red
hot : putting it in bottom downwards would be almost certain to
cause it to crack.
The pot is now bedded upon the fuel, and the brass-founder,
whilst making up the fire, puts an iron cover with a long central
handle over the mouth of the pot, to prevent the small cokes which
are now thrown on from entering the same. Next, the charge of
metal is put in the crucible, and three or four large pieces of coke
are placed across the mouth of the pot ; the tile is put on the fur-
nace, the damper is then adjusted to heat the crucible quickly, and
the whole is left to itself until the metal is run down.
The gold and silver refiners and jewelers manage their furnaces
much in the same way, except that they support the crucible upon
a hollow earthen stand placed on the fire-bars to catch any leakage,
and also put an earthen cover over its mouth. They generally use
coke, although charcoal is a purer fuel, and is laid upon the fluid
metals to prevent oxidation. The above, and the so-called blue
pots, or black-lead pots, are not burned until they are put into the
fire for use ; but the Hessian pots, the English brown or clay pots,
the Cornish and the Wedgwood crucibles, are all burned before
use.
It may be further observed, that the pots for brass are too porous
for gold and silver, as they suck up too much of the same : the
black-lead pots are closer and better for the precious metals, and
they withstand change of temperature best of any kind ; they are
however the most expensive, but cannot be safely used with fluxes.
The Hessian crucibles resist the fluxes, and serve with care for
several consecutive meltings ; the English clay pots, which resem-
ble the Hessian, are safe for one or sometimes for more meltings,
and their cost is trifling. The pots for gold and silver are occasion-
ally coated or luted externally with clay as a protection.
The generality of the metals are far more disposed to oxidation
when in the melted condition than when solid ; it is therefore usual,
whilst they are in the crucible, to protect their surfaces from the
air with some flux, to lessen their disposition to oxidize.
In the iron furnace, the slag from the lime floats on the metal
and fulfils this end ; many brass-founders always throw broken
glass, charcoal dust, sandiver, or sal-enixon, into the melting pot:
by others these precautionary measures are altogether neglected.
The black and white fluxes, borax, and saltpetre are also used for
the precious metals, and oil or resin for the more fusible, as lead or
tin ; but excess of heat should be at all times avoided.
224 THE PRACTICAL METALWORKER'S ASSISTANT.
The generality of the fusible metals may be mixed in all pro-
portions. Those in which the melting points are tolerably similar
may be easily combined, such as lead with tin, or gold with silver
or copper ; these appear to call for no instructions beyond modera-
tion in the heat employed, but the difficulty of making definite and
uniform alloys increases when the melting point of the metals, or
their qualities or quantities, are widely dissimilar.
In mixing alloys with new metals, it is usual to melt the less
fusible first, and subsequently to add the more fusible ; the mix-
ture is then stirred well together, and common opinion seems to be
in favor of running the metal into an ingot mould, as the second
fusion is considered more thoroughly to incorporate the mixture.
Sometimes, with the same view, the alloy is granulated, by pouring
it from the crucible into water, either from a considerable height
through a colander, or over a bundle of birch twigs, which subdi-
vide it into small pieces; others condemn such practices, and
greatly prefer the first fusion, in order to avoid oxidation, and de-
parture from the intended proportions.
But in many, and perhaps in most cases, it is the practice to fill
the melting pan, or the crucible, in part with old alloy, consisting
of fragments of .spoiled or worn-out work; and to which is added,
partly by calculation but principally by trial, a certain quantity of
new metals. This is not always done from motives of economy
alone, but from the opinion that such mixtures cast and work better
than those made entirely of new metals.
When small quantities of metal of difficult fusion, are added to
large proportions of others which are much more fusible, the whole
quantities are not mixed at once. Thus in pewter, it would be
scarcely possible to throw into the melted tin the half per cent, or
the one per cent, of melted copper with any certainty of the two
combining properly, and it is therefore usual to melt the copper in
a crucible, and to add to it two or three times its weight of melted
tin; this, as it were, dilutes the copper, and makes the alloys
known as temper, which may be fused in a ladle, and added in small
quantities to the fluid pewter or to the tin, as the case may be,
until on trying the mixture by the assay its proportions are con-
sidered suitable.
The metal for printers' type is often mixed nearly in the same
manner ; the copper is first melted alone in a crucible, the anti-
mony is melted in another crucible, and is poured into the copper ;
sometimes a little lead is also added. The hard alloy and the tin
are then introduced to the mass of type-metal or lead, also in great
measure by trial, as old metal mostly enters into the mixture.
The composition of Britannia metal is as follows : 8J cwt. of
best block tin ; 28 Ibs. of martial regulus of antimony ; 8 Ibs. of
copper, and 8 Ibs. of brass. The amalgamation of these metals is
effected by melting the tin, and raising it just .to a red heat in a
stout cast-iron pot or trough, and then pouring into it, firs* the
regulus, and afterwards the copper and brass, from the crucibles
MELTING AND MIXING THE METALS. 225
in which they have been respectively melted, the caster meanwhile
stirring the mass about during this operation, in order that the
mixture may be complete.
It would appear, however, much more likely and consistent that
a similar mode is adopted in making this alloy, as in pewter and
type-metal ; namely, that the copper and brass are melted together
in one crucible, the antimony then added from another crucible,
and perhaps also a little tin; this would dilute the hard metals, and
make a fusible compound, to be added to the remainder of the tin
when raised a very little beyond its fusing point, so as to maintain
fluidity when the whole were mixed and stirred together, pre-
viously to being poured into ingots. By this treatment the tin
would be much less exposed to waste.
When a very oxidizable or volatile metal, as zinc, is mixed with
another metal the fusing point of which is greatly higher, as with
copper for making the important alloy brass, whatever weight of
each may be put into the crucible, it is scarcely possible to • speak
with any thing like certainty of the proportions of the alloy pro-
duced, from the rapid and nearly uncontrollable manner in which
the waste of the zinc occurs.
Various means have been devised at different times for combin-
ing these two metals.
Although the most direct way of forming the different kinds of
brass is by immediately combining the metals together, one of
them, which is most properly called brass, was manufactured. long
before zinc, one of its component parts, was known in its metallic
form. The ore of the latter metal was cemented with sheets of
copper, charcoal being present. The zinc was formed and united
with the copper, without becoming visible in a distinct form. The
same method is still practised for making brass.
The best way of uniting zinc with copper, in the first instance,
will be to introduce the copper in thin slips into the melted zinc,
till the alloy requires a tolerable heat to fuse it, and then to unite
it with the melted copper.
Some persons thrust the whale of the copper, in thin plates, into
the melted zinc, which rapidly dissolves them ; and the mass is
kept in a pasty condition until within a few minutes of the time '
of pouring, when they augment the heat to the degree required
for the casting process.
But the plan which is the most expeditious, and now most usu-
ally adopted, is to thrust the broken lumps of zinc beneath the
surface of the melted copper with the tongs, which mode will be
more particularly described ; but howsoever conducted, a consid-
erable waste of the zinc will inevitably occur.
It is also certain that every successive fusion wastes, in sorn .:
degree, the more oxidizable metal, so that the original proportion
is more and more departed from, especially with the least excess of
heat ; and when the metals are not well covered with flux. The
loose oxide frequently mixes with the metal ; this in brass gives
15
226 THE PRACTICAL METAL- WORKER^ ASSISTANT.
rise to the white-colored stains, and the little cavities filled with the
white oxide of zinc ; and in gun-metal the stains and streaks are
blacker, and the oxide of tin (or putty powder) being much
harder than the former, is sadly destructive to the tools. The
vitreous fluxes collect these oxides, and are therefore serviceable ;
but when in excess, they are liable to run into the mould when the
metal is poured. The chemist generally uses covers to the cruci-
bles, to lessen the access of air, and therefore the oxidation ; but
the brass-founder frequently leaves the metal entirely uncovered.
No considerable waste occurs until the metal is entirely fused and
rather hotter than is required for pouring, which is indicated by
the zinc beginning to burn at the surface with a blue flame.
The loss which occurs in melting brass-filings is a proof that
the granulation of the metals is not always desirable ; and unless
the brass-filings are well drawn, by a group of magnets, to free
them from particles of iron and steel, the latter often spoil the cast-
ings, as they become so exceedingly hard as to resist the file or
turning- tool, and can be only removed by the hammer and cold-
chisel.
In collecting the several alloys given at pages 180 to 203, espec-
ially those of copper, I found great difficulty in reconciling many
of the statements derived from books ; and therefore, to place the
matter upon a surer basis, and also with some other views, I de
termined to mix a series of the copper alloys, in quantities of from
one to two pounds each, pursuing, as nearly as possible, the coin
mon course of foundry work, to make the results practical and
useful.
My first intention was to weigh the metals into the crucible, and
to find, by the weight of the product, the amount of loss in every
case, as well as the quality of the alloy. Commencing with this
view, with copper and zinc, the several attempts entirely failed,
owing to the extremely volatile nature of the latter metal, espec-
ially when exposed to the high temperature of melted copper.
The difficulty was greatly increased owing to the very large extent
of surface exposed to the air compared with that which occurs
when greater quantities are dealt with, and the increased rapidity
with which the whole was cooled.
The zinc was added to the melted copper in various ways,
namely, — in solid lumps, in thin sheets hammered into balls,
poured in when melted in an iron ladle : and all these, both whilst
the crucible was in the fire and after its removal from the same.
The surface of the copper was in some cases covered with glass or
charcoal, and in others uncovered, but all to no purpose, as from
one-eighth to one-half the zinc was consumed with most vexatious
brilliancy, according to the modes of treatment : and these methods
were therefore abandoned as hopeless.
I was the more diverted from the above attempts by the well-
known fact that the greatest loss always occurs in the first mixing
of the two metals, and which the founder is in general anxious to
MELTING AND MIXING THE METALS. 227
avoid. Thus, when a very small quantity of zinc is required, as
for the so-called copper casting, about 4 oz. of brass are added to
every 2 or 3 Ibs. of copper. And in ordinary work, a pot of brass
weighing 40 Ibs. is made up of 10, 20, or 30 Ibs. of old brass, and
two-thirds of the remainder of copper. These are first melted. A
short time before pouring, the one-third of the new metals, or the
zinc, is plunged in when the temperature of the mass is such that
it just avoids sticking to the iron rod with which it Is stirred.
In mixing the copper and zinc for my experiments on brass, an
entirely different course was therefore determined upon, namely,
to melt the metals on a large scale, and in the usual proportion-
that is, 24 Ibs. of copper to 12 Ibs. of zinc — to learn the first loss
of zinc when conducted with ordinary care. Then to remelt a
quantity of the alloy over and over again, taking a trial-bar every
time in order to ascertain the average loss of zinc in every fusion.
From the residue of the original mixture, to make the alloys con-
taining less zinc, by a proportional addition of copper ; and those
alloys containing more zinc, by a similar addition of zinc. And
lastly, to have the whole of the bars assayed, to determine the ab-
solute proportion of copper and zinc contained in all, and from
these analyses to select my series of specimens, as nearly in agree-
ment as I could with the proportions in common use. This method
answered every expectation.
Twenty-four pounds of copper, namely, clean ship's bolts, were
first melted alone to ascertain the loss sustained by passing through
the fire, which was found to be barely J oz. on the whole. A simi-
lar weight of the same copper was weighed out, and also 12 Ibs.
of the best Hamburg zinc, in cakes about f inch thick, which
were broken into pieces.
The copper was first melted, and when the whole was nearly
run down the coke was removed to expose the top of the pot,
which was watched until the boiling of the copper, arising probably
from escape of bubbles of air locked up at the lower part of the
semi-fluid mass, ceased, and the copper assumed a bright red but
sluggish appearance. The zinc was then added.
Precaution is necessary in introducing the first quantity of zinc
not to set the copper, which is liable to occur if a large quantity
of cold metal is thrown in, simply from the abstraction of heat ;
and it is also necessary to warm the zinc, that it may be perfectly
dry, as- the least moisture would drive the metal out of the pot
with dangerous violence. A small • lump of zinc, therefore, was
taken in the tongs, held beside the pot for a few moments, and then
put in with the tongs with an action between a stir and a plunge,
regardless of the flare, and of the low crackling noise, just as if
butter had been thrown in. The zinc was absorbed, and the sur-
face of the pot was clear from its fumes almost immediately. The
remainder of the zinc was then directly added, in about eight
pieces, one at a time, much in the same manner, but the danger of
setting the copper nearly ceases when a small quantity of the
228 THE PKACTICAL METAL-WORKER'S ASSISTANT.
spelter is introduced. After every addition the pot was free from
flame in a few moments. A handful of broken glass was then
thrown in, the tile replaced, and the whole allowed to stand for
about fifteen minutes to raise the metal to the proper heat for
pouring, which is denoted by the commencement of the blue fumes
of the zinc.
The pot was then taken from the fire, well stirred for one minute,
and poured; the weight of the brass yielded was 34 Ibs. 12 J oz.,
showing a loss of 1 Ib. 3 J oz., or one-tenth of the zinc, or the one-
thirtieth part of the whole quantity. This experiment was re-
peated, and the loss was then 1 Ib. 3 oz., the difference being only
J an oz. By analysis, the mean of the two brasses was 31 J per
cent, zinc ; or instead of being 8 oz. to the pound, it was only 7 J oz.
Twelve pounds of each of these experimental mixtures were re-
melted six times, a bar weighing about one pound and a half-being
taken every time ; the two series of trials were conducted in differ-
ent foundries, by different men, and quite in the ordinary course of
work ; but the loss per cent, of zinc was in the six experiments ex-
actly alike in each series, that is, each bar, after the sixth melting,
contained 22 J per cent, or 4f oz. to the pound of copper. The
second fusion in each case sustained the greatest loss, (say nearly
two-fold ;) and in the others, taking all the accidental circumstances
into account, the loss might be pronounced nearly alike every
fusion
In making the alloys with more zinc ; the calculated weight of
the first alloy was melted, and the amount of zinc was warmed and
plunged in with the tongs, whilst the pot was in the fire, the whole
was stirred and quickly poured : the losses in weight were rather
large, but this is common when the zinc is in great quantity. To
make the alloys containing less zinc than the alloy, the calculated
weight of copper was first made red-hot and the respective portion
of the brass alloy was then put in the pot, by which means the two
ran down nearly together : it being found that the copper, if en-
tirely melted before the brass was added, incurred a risk of being
set at the bottom of the pot ; and remelting the mass, wasted the
zinc. These alloys came out much nearer to their intended
weights.
In making the tin and copper alloys, very little difficulty was
experienced. The copper was put into the pot together with a'
little charcoal, which was added to assist the fusion and also to
cause the alloy to run clean out; as in pouring gun- metal a small
quantity is usually left on the lip of the crucible, which would have
been an interference in these experiments. When the copper had
ceased boiling, and was at a bright red heat, it was taken from the
fire, and the tin previously melted in a ladle, was thrown in ; every
mixture was well stirred and poured immediately.
In the fourteen alloys thus formed, each weighing about a pound
and a half, namely, J, 1, 1 J, etc., up to 8 oz. of tin to the pound of
copper, (missing the 6J and 7J,) no material loss was sustained in
MELTING AND MIXING THE METALS. 229
nine instances, and in the other five it never exceeded J- oz., and
that quantity was probably lost rather in fragments than by
oxidation. «.
Alloys of 2, 4, 6 and 8 ounces of lead to the pound of copper,
were made exactly under the same circumstances as the last.
Messrs. Barron and Brother, of New York, manufacture a very
effective and economical furnace, which supplies the necessary
quantity of air ; for in the combustion of fuel only a certain quantity
of air is required, either an excess or deficiency is prejudicial to
proper combustion.
The metals are melted by this furnace in less time, and at a less
expense of fuel than any that have fallen under my notice.
In less than ten minutes, gold, silver, and copper can be melted
by the furnace of Barron and Brother. The first size will melt
from 4 to 12 ounces of gold with about a quart of coal ; the second
size will melt 50 to 120 ounces with about two quarts ; and the
third size will melt from 100 to 500 ounces with three or four
quarts of coal.
It is a difficulty of no ordinary description to ascertain the tem-
perature of a furnace with sufficient accuracy. Every fire and
every furnace is continually changing its temperature. When a
furnace is charged with a fresh supply of fuel, its temperature is
lowered by the absorption of heat which the cold fuel takes up
when thr.own upon the fire.
The temperature is lowered by a rush of cold air through the
open door. Experiments made by the pyrometer showing the
mean temperature of the flues in a steam-engine boiler, and the
effects produced by the admission of air through a permanent and
regulated apparatus behind the bridge, indicate that in making the
quantity of water evaporated by one pound of coal as the measure
of economy, the mean of nearly the whole experiments is about
12 J per cent, in favor of a regulated and continuous supply of air.
In order to insure economy and effect in the combustion of fuel, a
large supply of air must be admitted to the furnace, and that in the
ratio of 10 volumes of air to 1 of coal gas. Perfect combustion is
the prevention of smoke. And it is found that in order to render
the residue of the products of combustion transparent or smokeless,
a supply of air amounting to ten times the gases evolved must be
admitted.
230 THE PRACTICAL METAL- WORKER'S ASSISTANT.
CHAPTER XV.
\
CASTING AND FOUNDING.
METALLIC MOULDS. — We are indebted to the fusibility of the
metals, for the power of giving them with great facility and per-
fection, any required form, by pouring them whilst in the fluid state
into moulds of various kinds, of which the castings become in
general the exact counterparts. This property is of immeasurable
value.
Some few objects are cast in open moulds, so that the upper sur-
face of the fluid metal assumes the horizontal position the same as
other liquids, as in casting ingots, flat plates, and some few other
objects ; but in general the metals are cast in close moulds, so that
it becomes necessary to provide one or more apertures or ingates
for pouring in the metal, and for allowing the escape of the air
which previously filled the moulds.
When these moulds are made of metal, they must be sufficiently
hot not to chill or solidify the fluid metal before it has time to
adapt itself thoroughly to every part of the mould : and when the
moulds are made of earthy matters, although moisture is essential
to their formation, little or none should remain at the time they
are filled.
The earthen moulds must be also sufficiently pervious to air,
that any vapor or gases which may be formed, either at the mo-
ment of pouring in the metal or during its solidification, may have
free vent to escape ; otherwise, if these gases are rapidly formed,
there is great danger of the metal being driven out of the mould
with a violent explosion, or when more slowly formed and locked
up without sufficient freedom for escape, the casting will be said
to be blown, as some of the bubbles of air will displace the fluid
metal and render it spongy or porous. It not unfrequently hap-
pens that castings which appear externally good and sound, are
full of hidden defects, because the surface being first cooled, the
bubbles of air will attempt to break their way through the central
and still soft parts of the casting.
The explanatory diagram, Fig. 120, is intended to elucidate some
of the circumstances concerning the construction of moulds, which
in the greater number of cases are made only in two parts, but in
other cases are divided into several. The figure to be moulded is
supposed to be a rod of elliptical section, the mould for which
might be divided into two parts through the line A, B, because no
part of the figure projects beyond the lines a, b, drawn from the
margin of the model at right angles to the line of division, and in
which direction the half of the mould would be 'removed or lifted,
the model could be afterwards drawn out from the second half of
the mould in a similar manner.
CASTING AND FOUNDING.
231
The mould could be also parted upon the line C, D, because in
that direction likewise, no part of the model extends beyond the
lines c, d, which show the direction in which the mould would be
then lifted.
Fig. 120.
F
The mould, however complex, could be also parted either upon
A B or C D, provided no part of the model outstepped the rect-
angle formed by the dotted lines b, c, or was undercut.
But considering the figure 120 to be turned bottom upwards, and
with the line E, F, horizontal, the removal of the entire half of
the mould upon the lines e,f, would be impossible, because in rais-
ing the mould perpendicularly to E, F, that portion of the mould
situated within the one perpendicular e, would catch against the
overhanging part of the oval towards A. Were the mould of metal,
and therefore rigid, it would be entirely locked fast, or it would
not " deliver ;" were the mould of sand, and therefore yielding, it
would break and leave behind that part between A and E which
caused the obstruction. Consequently, in such a case, the mould
would be made with a small loose part between A and E; so that
when the principal portion, from A to F, had been lifted perpendic-
ularly or in the direction of the line e, the small undercut piece.
A to E, might be withdrawn sideways, on which account it would
be designated by the iron founder a drawback, by the brass founder
a false core.
All the patterns in the mould, Fig. 121, could be extracted from
each half the mould, because none of them encroach beyond the
perpendicular line, or that in which the mould is lifted ; a and b,
could be laid in exactly upon the diagonal, or upon one flat side,
or partly embedded ; and in like manner / g, h, might be sunk
more or less into the mould, their sides being perpendicular ; but
the patterns in Fig. 122 being undercut, the division of the mould
into two parts only would be impracticable, and false cores or sub-
divisions would be required in the manner represented, the con-
struction of which will be hereafter detailed.
Extending these same views to a more complex object, such as
a bust, it will be conceived that the mould must be divided into
232
THE PRACTICAL METAL-WORKERS ASSISTANT.
so many pieces, that none of them will be required to embrace
any overhanging part of the figure. For instance, were it attempted
to mould a human head, so that the parting might pass through
the central line of the face and down the back, the two halves
could not be separated if they were made each in a single piece ;
as the inner angles of the eyes, the spaces behind the ears, and the
curls of the hair would obstruct it, and the head could be only
thus moulded by making false cores or loose pieces at these par-
ticular places, in the manner illustrated by the former figures.
These would require to be accurately adapted to the surrounding
parts, by pins and contrivances to ensure their re-taking their
true positions. These remarks, however, are only advanced by
way of general illustration, as figure casting is the most refined
part of the art of moulding.
Metal moulds are employed for many works in the easily-fused
metals, which are required to be produced in large quantities, and
with great similitude and economy: the examination of which
moulds will serve to demonstrate many of the points of construc-
tion and proceeding. Thus the common bullet mould is made
like a pair of pliers, the jaws of which are conjointly pierced with
a hole or passage leading into a spherical cavity ; the aperture is
equally divided between the two halves of the mould, so that in
fact the division is truly upon the diametrical line both of the
sphere and the runner, or the largest part of each, otherwise the
pliers could not be opened to remove the bullet when cast. Iron
shot for great guns are likewise cast in iron moulds, by which
they also possess great accuracy of form and size.
Figs. 123
124.
CASTING AND FOUNDING. 233
Figs. 123 to 126 represent the moulds for casting pewter ink-
stands: these moulds are a little more complex, and are each made
in four parts ; the black portions represent the sections of the ink-
stands to be cast. The moulds each consist of a top piece or cap t,
a bottom or core b, and two sides or cottles, s s ; in Fig. 126, the one
Figs. 125 126.
si« tu Is removed, in order to expose the casting, and the top piece /
is stx^-posed to be sawn through to make the whole more distinct.
It will be seen, the top and bottom parts have each a rebate like
the lid of a snuff-box, which embraces the external edges of the
two side pieces s s, and the latter divide as in the bullet mould,
exactly upon the diametrical line of the inkstand, which in a cir-
cular ol.ject is of course the largest part ; the positions of the parts
are therefore strictly maintained.
When the mould has been put together, laid upon its side, and
filled through x, the ingate, or as it is technically called, the tedge,
it is allowed to stand about a minute or two, and then the top t, is
knocked oiT by one or two light blows of a pewter mallet ; the
mould is then held in the hand and the bottom part or core is
knocked out of the casting by the edge ; lastly, the two sides are
pulled asunder by their handles, and the casting is removed from
the one in which it happens to stick fast ; but it requires cautious
handling not to break it. The face of the mould is slightly coated
with red ochre and white of egg, to prevent the casting adhering
to the same, aad to give the works a better face ; the first few
castings are generally spoiled, until in fact the mould becomes
properly warmed.
Most of the works made in the very useful material, pewter,
are cast in gun-metal moulds, which require much skill in their
construction ; thus a pewter tankard, with a hinged cover and
spout, consists of six pieces, every one of which requires a dif-
ferent mould; thus,
1. The body has a mould in four parts, like that for the inkstand,
but it is filled in the erect position through two ingates, which are
made through the top piece t, of the mould :
2. The bottom requires a mould in two parts, and is poured at
the edge :
3. The cover is cast in the same manner; and thus far the
THE PRACTICAL METAL-WORKER^ ASSISTANT.
moulds are all made in the lathe, in which useful machine these
> 127 128. castings are also finished be-
fore being soldered together :
4. The spout requires a
mould in two parts :
5. The piece, Fig. 128, by
which the cover is hinged to
the handle, requires a much
more complex mould, which
divides in four parts, as shown
in Fig. 127, and much resem-
bles, except in external form, the remaining mould : namely,
6. For the handle, which mould, like the last consists of four
pieces fitted together with various ears and projections; they are
represented in their relative positions in Fig. 130, with the excep-
tion of the piece a, Fig. 131, which is detached and shown bottom
upwards. Fig. 129 shows the pewter handle separately, with the
three knuckles for joining on the cover : and on reference to Fig.
130, of the five parts through which the pin p, is thrust, the two ex-
ternal pieces belong respectively to the sides c, and d, of the mould,
the others are parts of the casting, and the two hollows are formed
by the two solid knuckles fixed to the detached piece of the mould
a, Fig. 131. At the time of pouring, the pin p, serves to connect
the three parts a, c, d, together, and also to form the whole in the
casting, for the pin of the joint.
Figs. 129
130
Fig. 132 shows the section of the mould upon the dotted line s :
by this it will be seen the handle is cast hollow, as almost imme-
diately the mould has been filled through t, all but the thin exter-
nal shell is poured out again, and the weight is reduced to less
than half. To extract the handle the pin p is first twisted out ;
CASTING AND FOUNDING.
235
then the. joint piece a, is removed : next the back piece b ; and
lastly the two sides c, d, are pulled asunder.
Tin or pewter bearings for locomotive carriages, have been cast
in appropriate metal moulds ; and such materials are very useful
to the mechanist for many temporary purposes, such as collars,
bearings, screws and nuts, either for difficult positions, or where no
screw tap is at hand and the resistance is moderate ; in such cases
the parts of the machine constitute one portion of the mould, the
apertures being closed with moist loam : the processes are most
successful when the parts can be made warm and the clay is nearly
dry.
The most important; exact, and interesting example of casting
in metallic moulds is that of type-founding, the description of
which, as well as drawings of the mould, have been repeatedly
given ; some of the peculiarities only of this art, will be therefore
noticed. Each complete set of types consists of five alphabets. A,
A, a, A, a, besides many other characters, in all about two hun-
dred, and which are required to be most strictly alike in every
respect, except in device and width ; the width is the greatest for
the W and M, and the least for the i and I. Every required mea-
sure of the types (represented on an enlarged scale in Fig. 133), is
determined by the mould alone, and not by any after correction.
Figs. 133
1 tl ifllllllfk
138 134
If the moulds for the rectangular shafts of the types
as in Figs. 134: or 135, the usual forms of square mou'cte, chey
would not admit of alteration in width, as shilling o, /ig. 134,
would produce no change, and Fig. 135 would thereby produce
the form b. The mould which is used is made in two L formed
parts, as in Fig. 136, whence it follows that shifting the part a, to
the right or left increases or decreases the width of the type with-
236 THE PRACTICAL METAL- WORKER'S ASSISTANT.
out interfering with its thickness, or, as it is technically called, its
body. (B, Fig. 133,) the width, w, is adjusted by a piece called the
register, fixed at the bottom of the mould.
The device is changed by placing across the bottom of the mould
one of the two hundred little pieces of copper, Fig. 137, called
matrices, into which the face of the latter is impressed by very
beautifully formed punches The length of the letter is deter-
mined by contraction at the upper part of the mould, as shown at
c, Fig. 138, which represents the type as it leaves the mould ; the
metal is poured with a jerk, to make a sharp impression of the
matrix : the mould, which is held in the left hand, and the ladle in the
right, being jerked simultaneously upwards, at the moment of fill-
ing the mould, and without which the face of the type would be
rounded and quite imperfect. The breaks c, or the runners of the
types, are first broken off, and after a slight correction of the sides,
the hollows or channels in the feet are planed out of a whole col-
umn of them, fixed between bars of wood, without touching the
square shoulders which determine the lengths of the types, and
are left as originally cast.
In some types with a large face and much detail, such as the
illustrations given on the last page, the motion of the hand is
barely sufficient to give the momentum required to throw the me-
tal into the matrix, and produce a clean sharp impression. A
machine is then used, which may be compared to a small forcing-
pump, by which the mould is filled with the fluid metal ; but from
the greater difficulty of allowing the air to escape, such types are
in general considerably more unsound in the shaft or body ; so
that an equal bulk of them only weigh about three-fourths as
much as types cast in the ordinary way by hand, and which for
general purposes is preferable and more economical.
Some other variations are resorted to in type-founding ; some-
times the mould is filled at twice, at other times the faces of the
types are dabbed, (the clichee process ;) many of the large types and
ornaments are stereotyped, and either soldered to metal bodies, or
fixed by nails to those of wood. The music type, and ornamental
borders and dashes, display much very curious power of combina-
tion.
The clichee process is rather stamping than casting. The melted
alloy is placed in a paper tray, and stirred with a dard until it as-
sumes the pasty condition. The metal die, or mould, is then " dab-
bed" upon the soft metal, as in scaling a letter, but with a little
more of sluggish force.
By the type-founding machine invented by Mr. Pruce, of N. 'Y.,
and employed in the extensive foundry of Collins ai:d M'Leester, of
Philadelphia, 3600 letters may be cast in an hour, much more
sound and as perfect as those cast by hand.
PLASTER OF PARIS MOULDS AND SAND MOULDS. — Other exam-
ples of metallic moulds might be given, but there are far more
frequent cases in which one single casting is alone required ; or
CASTING AND FOUNDING 23?
else the number is so small, or the pieces themselves are so large
or peculiar, that the construction of metal moulds would be found
almost or quite impracticable, even without reference to an equally
fatal barrier, the expense.
In making these single copies in the metals of considerable fusi-
bility, plaster of Paris is sometimes employed ; thus, after the
printer has arranged the loose types into a page, and the requisite
corrections have been made, a stereotype, or solid type, is taken of
the whole as a thin sheet of metal, which serves to be printed from
almost as well as the original letters : and its small cost enables the
printer to retain it for future use, after the types themselves have
served perhaps for a hundred similar regenerations, and are ulti-
mately worn out.
The stereotype founder takes a copy of the entire mass of type
in plaster of Paris ; this is dried in an oven, and placed face down-
wards within a cast-iron mould, like a covered box, open at the
four top-corners. The mould and plaster-cast are heated to the
fusing temperature of the type-metal, and gradually lowered into a
pan or bath of the same by means of a crane ; the hot fluid metal
runs in at the corners of the mould, and raises the inverted plas-
ter, which latter would rise entirely to the surface but for the
restraint of the cover of the mould.
Type-metal is about eleven times as heavy as water ; and if the
mould be immersed four inches below the surface, it is subjected to
a pressure equal to that of a column of water forty-four inches
high, or above two pounds upon every square inch.
The necessity of this arrangement is shown when a few ounces
of type-metal are poured from a ladle on the face of the plaster ;
the metal looks like a dump, almost without any mark of the let-
ters, whereas the stereotype-cast is nearly as sharp as the original
type. The immersion fulfils the same end as the jerk of the
hand-caster, or of the pump occasionally employed : and the long
continuance of the mould in the fluid metal allows ample time for
the air to escape in bubbles to the surface ; after which the mould
is raised and cooled in a vessel of water, and the plaster is mostly
destroyed in its removal.
Plaster of Paris, although it may be, and frequently is used for
the fusible metals, such as lead, tin, and pewter, cannot be em-
ployed alone for iron, copper, brass, and many other metals, the
intense melting heats of which would calcine the material, and
cause it to crumble ; even the soft metals should not be very hot,
or they will make the plaster of Paris blister off in flakes or dust.
We must therefore seek a substitute better capable of enduring
the heat, and likewise susceptible of receiving definite forms ; for
which purpose damp sand, with a small natural or subsequent
admixture of clay or loam, is found to be perfectly adapted.
The moulding-sand cannot, however, be used without external
support, and which is given by shallow iron frames without tops or
bottoms, called flasks, rjp resented in Figs. 139 and 1-JtO. The bot-
238
THE PRACTICAL METAL-WORKER'S ASSISTANT.
torn part, 4, 5, is supposed to have been rammed full of sand, and
to stand upon a flat board, 6. The model of the plain flat bar
which is to be cast, is now laid on the surface of the sand, that of
Fig. 139.
Fig. 140.
the round bar is imbedded half way in the same, and the mould is
dusted with dry parting sand.
The top part of the flask 2, 3, is shown, still empty, and in the
act of being attached to 4, 5 by its pins, which enter corresponding-
holes in the latter, easily but without shake : 2, 3 is also rammed
full of sand, and covered with a top board, 1, not represented to
avoid confusion. The mould is now opened, the models are removed,
and channels are scooped out from the ends of the cavities left by
the models, to the hollows or pouring-holes at the end of the flask:
the parts are all replaced in the order 1 to 6, represented in Fig.
139, and the whole are fixed together by screw clamps, so as to
assume the condition of Fig. 140.
The flask is now placed almost perpendicularly beside the pour-
ing-trough, and the metal is poured into it from the crucible, as
shown in Fig. 119, p. 221; but the flask, if small, is put on the sur-
face of the pouring or spill-trough, and propped up with a short
bar.
This brief sketch of the entire process of moulding and casting
in sand moulds, will be now followed by some remarks in greater
detail : first on the patterns of the objects to be cast ; secondly, on the
conditions required in the sand; and thirdly, the process of mould-
ing simple and solid bodies. The section then following will be
devoted to moulding cored works, and figures, after which a few
lines will be given upon the subject of filling the moulds.
PATTERNS, MOULDS, AND MOULDING SIMPLE OBJECTS. — The
perfection of castings depends much on the skill of the pattern-
maker, who should thoroughly understand the practice of the
moulder, or he is liable to make the patterns in such a manner
that they cannot be used, or at any rate be well used.
CASTING AND FOUNDING. 239
Straight-grained deal, pine, and mahogany, are the best woods
lor making patterns, as they stand the best ; screws should be used
in preference to nails, as alterations are then more easily made in
the models, and glue joints, such as dovetails, tenons, and dowels,
are also good as regards the after use of the saw and plane for cor-
rections and alterations.
Foundry patterns should be always made a little taper in the parts
which enter most deeply into the sand, in order to assist their removal
from the. same, when their purposes will not be materially interfered
with by such tapering. The pattern-maker, therefore, works most
of the thickness, and the sides or edges, both internal and external,
a little out of parallel or square, perhaps as much as about one-six-
teenth to one-eighth of an inch in the foot, sometimes much more.
When foundry patterns are exactly parallel, the friction of the
sand against their sides is so great when they penetrate deeply,
that it requires considerable force to extract them ; and which vio-
lence tears down the sand, unless the patterns are much knocked
about in the mould, to enlarge the space around them. This rough
usage frequently injures the patterns, and causes the castings to
become irregularly larger than intended, and also defective in point
of shape, from the mischief sustained by the moulds; all which evils
are lessened when the patterns are made consistently taper and
very smooth.
It must be distinctly and constantly borne in mind, that although
patterns require all the methods, care, and skill, of good joinery or
cabinet-making, they must not, like such works, be made quite
square and parallel, for the reasons stated. Sharp, internal angles
should in general be also avoided, as they leave a sharp edge or
arris in the sand, which is liable to be broken down in the removal
of the pattern ; or to be washed down on the entry of the metal
into the mould. Either the angle of the model should be filled
with wood, wax, or putty, or the sharp edges of the sand should
be chamfered off with the knife or trowel. Sharp internal angles
are very injudicious in respect also to the strength of castings, as
they seem to denote where they will be likely to break ; and more
resemble carpentry than good metallic construction.
Before the patterns reach the founder's hands, all the glue that
may have been used in their construction should be carefully
scraped off, or it will adhere to and pull down the sand. The be.st
way is to paint or varnish wooden patterns, so as to prevent them
from absorbing moisture, as they will then hang to the sand much
less, and will retain their forms much better. Whether painted or
not, they deliver more freely from the mould when they are well
brushed with black lead, like a stove.
In patterns made in the lathe, exactly the same conditions are
required ; the parts which enter deeply into the sand should be
neither exactly cylindrical nor plane surfaces, but either a little
coned, or rounding, as the case may be ; and the internal angles
should not be turned exactly to their ultimate form, but rather
240 THE PRACTICAL METAL-CORKER'S ASSISTANT.
filled in, or rounded, to save the breaking down of the sharp edges
of the mould.
Foundry patterns are also made in metal ; these are very excel-
lent, as they are permanent; and when very small are less apt to
be blown away by the bellows used for removing the loose sand
and dust from the moulds. To preserve iron patterns from rust-
ing, and to make them deliver more easily, they should be allowed
to get slightly rusty, by lying one night on the damp sand ; next,
they should be warmed sufficiently to melt beeswax, which is
then rubbed all over them, and in great part removed, and then
polished with a hard brush when cold. "Wax is also used by the
founder for stopping up any little holes in the wooden patterns ;
whitening is likewise employed, as a quicker but less careful expe-
dient ; and very rough patterns are seared with a hot iron. The
good workman, however, leaves no necessity for these corrections,
and the perfection of the pattern is well repaid by the superior
character of the castings.
Metal patterns frequently require to have holes tapped into them
for receiving screwed wires, by way of handles for lifting them out
of the sand; and in like manner, large wooden patterns should have
screwed metal plates let into them, for the same purpose, or the
founder is compelled to drive pointed wires into them, to serve as
handles, which is an injurious practice.
The flasks or casting-boxes for containing the sand, are made of
various sizes. Each side is about 2 to 3 inches deep. They are
poured at the edge when placed nearly vertical ; but for large brass
works the practice of the iron-founder is generally followed, who
mostly pours his work horizontally, through a hole in the top, as
will be explained. The pins of the flask should fit easily, but with-
out shake, or the two halves will shift about and cause a disagree-
ment or slip in the casting. The tools used in making the moulds
are few and simple, namely, a sieve, shovel, rammer, strike, mallet,
a knife, and two or three loosening wires and little trowels, which
it is unnecessary to describe.
The principal materials for making foundry moulds are very fine
sand and loam. They are found mixed in various proportions, so
that the respective quantities proper for different uses cannot be
well defined; but it is always judicious to employ the least
quantity of loam^that will suffice. These materials are seldom
used in their new or recent states for brass castings, although more
so for iron, and the moulds made of fresh sand are always dried,
as will be explained.
The ordinary moulds are made of -the old damp sand, and they
are generally poured immediately, or whilst they are green ; some-
times they are more or less dried upon the face. The old working
fine sand is considerably less adhesive than the new, and of a dark-
brown color. This arises from the brick-dust, flour, and charcoal-
dust used in moulding becoming mixed with the general stock,
which therefore requires occasional additions of new sand or loam,
CASTING AND FOUNDING. 241
so that when slightly moist and pressed firmly in the hand it may
form a moderately hard compact lump.
Ked brick-dust is generally used to make the partings of the
mould, or to prevent the damp sand in the separate parts of the
flask from adhering together.
The face of the mould which receives the metal is generally
dusted with meal-dust, or waste flour ; but in large works, pow-
dered chalk, and also wood or tan ashes, are used, from being
cheaper. The moulds for the finest brass castings are faced either
with charcoal, loamstone, rottenstone, or a mixture of the same.
The moulds are frequently inverted and dried over a dull fire of
cork shavings, or when dried they are smoked over pitch or black
resin lighted in an iron ladle.
The gold and silver casters frequently use a lighted link for
facing their sand-moulds, and some of the type-founders' metallic
moulds are smoked over a lamp. All these modes deposit a fine
layer of soot upon the moulds.
The cores, or loose internal parts of the moulds for forming holes
and recesses, are made of various proportions of new sand, loam
and horse-dung, as will be explained in the section on cored works.
They all require to be thoroughly dried, and those containing
horse- dung must be well burned at a red heat ; this consumes the
straw and makes them porous, and of a brick- red.
In making the various moulds, it becomes necessary to pursue
a medium course between the conditions best suited to the forma-
tion of the mould and those best suited to filling them with the
red-hot metal without risk of failure or accident. Thus, within
certain limits, the more loam and moisture the sand contains, and
the more closely it is rammed, the better will be the impression
of the model ; but at the same time the moist and impervious con-
dition of the mould would then incur the greater risk of accident,
both from the moisture and from the non-escape of the air. There-
fore the policy, on the score of safety, is to use the sand as dry as
practicable, so as to avoid the delay of after-drying, and also to
keep the mould porous.
The founder, therefore, compromises the matter by using a little
facing sand containing rather more loam, for the face of the green
moulds for general work ; and in those cases where much loam is
used, the moulds are thoroughly dried by heat, which is not gen-
erally necessary with ordinary sand moulds.
The power of conducting heat is considerably less in red-hot
iron than in copper and brass, and therefore the moulds for the
latter require to be in a drier condition than those which may be
used for iron; but in either case the presence of superfluous
moisture is always attended with some danger to the individual as
well as to the work.
The above is the reason generally assigned for the fact that the
iron-founders may and do use their moulds with safety when sen-
sibly more moist than is admissible for brass and copper castings.
242 THE PRACTICAL METAL-WORKER'S ASSISTANT.
It is confirmatory of the fact that the more dense the mould,
the drier it must be, as the sand used by iron-founders is also
coarser and therefore more porous than that employed by brass-
founders.
Another point has also to be considered: as castings contract
considerably in cooling, in moulding large and slight works the
face of the mould must not be too strongly rammed, nor too much
dried, or its strength may exceed that of the red-hot metal whilst
in the act of shrinking. The result would be, that in contracting,
the casting would be rent or torn asunder from the restraint of the
mould ; whereas it should have the preponderance of strength, so
as to pull down the face of the sand instead of being itself de-
stroyed. But the exact condition both of the mould and of the
melted metal, must be determined by the nature of the object to be
cast, — matters which can be only referred to with the development
of the practice of the foundry, and upon which we shall now
commence.
The sand having been prepared, and the appropriate flask and
boards selected, the moulder first examines every pattern sepa-
rately to determine the most appropriate way of inserting it in the
flask, as explained by Fig. 121, p. 232 ; also to see that patterns,
such as / and h, therein shown, are smallest at the parts entering
the most deeply into the sand, in order that they may deliver well.
It should also be noticed whether they are perfectly smooth, and
that there is no glue hanging about them, which would cause them
to adhere and to pull down the moist sand.
The bottom flask, 4, 5, p. 238, is placed on a board not less than
an inch or two longer and wider than itself, with the face 4, down-
wards, and it is filled from the side 5. A small portion of the
strong facing-sand is rubbed through a fine sieve ; the remainder
is thrown in from the trough with the shovel, and the moulder
drives the whole moderately hard into the flask, either with a
mallet, the handle of the spade, or other rammer ; or else he jumps
up by aid of the rope suspended from the ceiling, and treads the
sand in with his feet. The surface is then struck off level with a
straight metal bar or scraper, a little loose sand is sprinkled on
the surface, upon which another board is placed, and rubbed down
close.
The two boards and the flask contained between them are then
all three turned over together. This requires them to be brought
to the front of the moulding-trough, so that the individual may
rest his chest against them, and his fore-arms upon the edges of
the top board ; he then grasps the three together at the back part
with his outstretched hands, and, thus retained in contact, the
whole are quickly turned over upon the front edge of the mould-
ing-trough, and then slid back upon the transverse bearers or
blocks to the usual position.
The top board is afterwards taken off, the clean surface of moist
sand, then exposed, is well dusted over with red brick-dust, crushed
CASTING AND FOUNDING. 243
fine, and contained in a linen bag. The mouth of the bag is held
in the right hand, and the bottom corner in the left, and both hands
are shaken up and down together to scatter the dry powder uni-
formly over the flask. A part of the loose powder is removed
with the hand-bellows, and the bottom half of the mould is then
ready for receiving the patterns.
The models are next arranged upon the face of the sand at 4,
so as to leave space enough to prevent the parts breaking one into
the other, and also for the passages by which the metal is to be
introduced, and the air allowed to escape. When there are only
two or three pieces to be cast, a separate runner is often made to
each of them from one of the holes in the end of the flask. When
several small patterns are to be moulded, they are arranged on
both sides a central runner, or ridge, from which small passages
lead into every section of the mould. The whole mass when
poured has been compared to a great fern leaf with its leaflets, and
is usually called a spray.
Those patterns which are cylindrical or thick, are partly sunk
in the sand by scraping out hollow recesses with the bowl of an
old copper spoon, and knocking the model into the sand with the
mallet. Afterwards the general surface is repaired to agreement
with the diametrical line of the model, or its largest section, as the
case may be, by means of a knife or a little piece of sheet steel,
something like the worn-out blade of a desert-knife bent up a little
at the end, or else with very small trowels.
After the sand is made good to the edges of the patterns, the
brick-dust is again shaken over them, so that the patterns may
receive a slight share as well as the general surface of the sand.
The upper part of the flask 2, 3, is then fitted to the lower, or 4, 5,
by the pins, and this half likewise is made up. First a little strong
sand is sifted in ; it is then filled up from the trough, rammed
down, and struck off as before, the dry powder serving to prevent
the two halves from sticking together.
In order to open the mould for the extraction of the models, a
board is placed on the top of flask 2, 3, and struck smartly at dif-
ferent parts with the mallet ; the tool is then laid aside and the
upper part of the flask and its board are lifted up very gently and
quite level, after which it is inverted on its board — and now each of
the inner faces of the mould is exposed. Should it happen that
any considerable portion of the mould, say a part as large as a
shilling, is broken down in one piece, the cavity is moistened with
the end of the knife, the mould is again carefully closed, and
lightly struck before the removal of the patterns. It is probable
on the second lifting such piece will be picked up.
The breaks are carefully repaired before the extraction of the
patterns, to effect which they are driven slightly sideways with
blows of the mallet, given on a short wire or punch, so as to loosen
them by enlarging the space around them. The patterns are then
lifted out very carefully with the finger-nails, or sometimes a
24:4 THE PRACTICAL METAL-WORKER'S ASSISTANT.
pointed wire is driven a little way into the pattern to serve as a
handle to lift it by. This process requires some delicacy not to
tear away the sand, which accident must be carefully repaired,
sometimes by replacing the loose pieces, at other times with a little
new sand picked out of any unused part of the mould.
A steel wire, pointed and hardened, is convenient as a picker out.
and when fixed in the pattern and stuck sideways it serves as a
loosening bar likewise. f
. Should the flask only contain one or two objects, the ingate or
runner is now scooped out of the sand, so as to lead from the
object to the pouring hole, and when several objects are contained,
a large central channel, and lesser passages sideways, are made as
before mentioned. The entrance round about the pouring hole is
smoothed and compressed with the thumb that it may not break
down when the metal is poured, and all the loose sand is care-
fully blown out of the mould, both parts of which may be placed
edgeways for the more convenient application of the bellows if
necessary.
The succeeding processes are to dust the faces of both halves of
the mould with meal dust or waste flour, as explained with regard
to the brick-dust, and to replace the mould and boards. The whole
of them are then carried to the spill-trough, upon the edge of
which they are rested whilst the one board is placed exactly level
with the end of the flask, but the board on the side from which
the crucible will be poured, is placed about two inches below, as
in Fig. 140, p. 238, and the hand-screws are fixed on as shown.
The mould is now held mouth downwards, that any sand loosened
in the screwing down may be allowed to fall out, and the flask,
according to its size, is supported either on the ground or on the
surface of the t rough by aid of a little bar resting against the
clamp. It is now quite ready to be filled — the. particulars of
which process will be described when the remarks on moulding
are concluded.
In works that require the first side or 3, 4 to be cut away for
embedding the models, it is usual when the second part or 2, 3 has
been made, to destroy the first or false side (which is only hastily
made), and to repeat it in a more careful manner by inverting the
lower flask upon 2, 3, proceeding in all other respects as before,
by which means a much more accurate and sound mould is pro-
duced.
When many copies of the same patterns are required, an odd side
is prepared, that is, a flask is chosen to which there are two bottom
sides, 4, 5. One of these latter is very carefully arranged with all
the patterns, but which are only embedded barely half way, so that
when 2, 3, is filled and both are turned over, the whole of the pat-
terns are left in the new side ; a second side, 4, 5, is moulded to
serve for receiving the metal, as the mould is destroyed every time
the metal is poured in. By this plan the trouble of re-arranging
the patterns for every separate mould is saved, as they are merely
CASTING- AND FOUNDING. 245
replaced in the odd side, and the routine of forming the two work-
ing sides is repeated.
MOULDING CORED WORKS. — If the objects to be cast require to be
so moulded that when they leave the sand they may contain one or
several holes, they are said to be cored, and in such cases, a variety
of methods are practised for introducing internal moulds or cores,
which shall intercept the flow of the metal, and prevent it from
forming one solid mass at those respective parts. For example,
the pins inserted in the pewterers' moulds, Figs. 127 and 130;
page 234, for producing the holes in the joints, are essentially
cores. Yarious other methods are pursued, the three most usual
of which are represented in Figs. 141, 142, and 143 : the upper fig-
ures show the exact sections of the three models or casting pat-
terns ; the lower figure represents the two halves of the mould,
which are respectively shaded with perpendicular and horizontal
lines, the cores are shaded obliquely ; and the white open spaces
show the hollows to be occupied by the metal when it is poured in.
First. Many works are said to deliver their own cores ; of such
kind is Fig. 141, in which the cavity extends through the model,
and exactly represents that which is required in the casting ; the
hole is either made quite parallel, or a little larger one side than
the other, and gradually taper between the two. In some cases,
when the hole is sufficiently taper, it delivers its own core as a con-
tinuation of the general mass of sand filling the one side of the flask ;
but in many or most cases, the space in the model is rammed full of
strong sand at first, and it is then moulded as if to produce a plain
solid casting. Before the mould is finally closed for pouring, the
sand core is pushed carefully out of the pattern, and inserted in the
mould ; to denote its precise position, one side of the core is scored
with one or two deep marks in the first instance, which cause
similar ridges or guides in the mould.
Secondly. When the hole extends only part way through, the
hole of the pattern, Fig. 142, is fitted with a solid plug, sawn and
filed out of soft unburnt brick, principally sand (or the common
Figs. 141 142 143.
Flanders brick), the core is made long enough to project about as
much as its own diameter, and the work is moulded as if to be
cast with a solid pin; instead of a hole. The last step is to extract
246
THE PRACTICAL METAL-WORKERS ASSISTANT.
the filed core, and to insert it into the hollow formed by itself in
the flask.
Thirdly. The patterns for iron work and some others are mostly
made with prints instead of holes, as in Fig. 143 ; that is, the pat-
tern-maker places square or round pieces on one or both sides of
the pattern, where the square or round holes are respectively
required ; and the founder has moulds for forming cores of corres-
ponding diameters or sections, and in lengths of about two to twelve
inches ; short pieces of which are cut off as may be required.
For example, some core-boxes are made like Fig. 144, for cylin-
drical cores ; these divide through the axis, and are kept in posi-
tion by pins ; at the time when they are rammed they are fixed
together by wood or iron staples, embracing three sides of the
mould, or else by screw clamps. For straight cores, say one inch
wide, twelve inches long, and half-inch thick, the pieces of wood,
Fig. 145, are also one inch thick, with an opening between them
of twelve inches long and half-inch wide. This core-box is laid
on a flat board, it is also held together with clamps, but without
pins in the core-box, as the projection at the one end gives the
rition ; it is rammed flush with both sides, and the two parts can
then separated obliquely. If it is preferred to make the cores
to the precise lengths instead of cutting them off, this core-box
admits of contraction in length, in the manner of the type mould,
Fig. 136, p. 235, and by placing thin slips between the two halves
it may be temporarily increased in width but not in thickness.
Fig. 146 is a similar core-box for a casting with circular mortises ;
this requires pins or projections at each end, as it cannot be opened
obliquely. Core-boxes are sometimes made of plaster of Paris,
wood is much better, and metal is the best of all.
Many works require core-boxes to be made expressly for them ;
thus the dotted line in Fig. 144 shows an enlargement in the centre
for coring a hole of that particular section. Figs. 147 and 148
represent the two halves of a brass or lead core-box suitable to the
Figs. 144
146
150 149
148
147.
stop-cock, Fig. 149 ; and Fig. 150 shows the core itself after its
removal from the part 148 in which it is also figured. In 149, the
CASTING AND FOUNDING.
247
model fr.om which the object is moulded, the shaded parts repre-
sent the projections, or core-prints, which imprint within the mould
the places where the extremities of the core, Fig. 150, are sup
ported when placed therein.
The various kinds of core-boxes are rammed full of new sand,
sometimes with extra loam ; the long cores are strengthened by
wires ; they are carefully removed from the boxes and thoroughly
dried before use, in the oven prepared for the purpose.
Others perfer sand, horse-dung, and a very little loam, for mak-
ing cores ; these are dried, and then well burned, for which purpose
they are put into an empty crucible within the fire, the last thing
at night, and allowed to remain until the morning. This consumes
the small particles of straw, and renders them more porous, in
consequence of which the works become sounder from the free
escape of air, the necessity of which was adverted to in the earlier
part of this subject, and cannot be too much insisted upon.
Fig. 151 represents several examples of coring : in this view the
works are represented of their ultimate forms, that is, with the
holes in them ; in Fig. 152, the models are arranged in the flask,
Fig. 151
152
with the runners all prepared, the prints of the cores being in every
case shaded for distinction. Thus a is the stopcock, of which ex-
planation has been already given ; b, has a straight and a circular
mortise ; this pattern delivers its own core, in the manner referred to
in Fig. 141, as the model is made with mortises like the finished
work : c only requires a perpendicular square core ; d, a round core
parallel with the face of the flask, and in this manner all tubes and
sockets are ca*st whether of uniform or irregular bore, see Fig. 144 ;
e, has two rectangular cores crossing each other at right angles :
248 THE PRACTICAL METAL-WORKER'S ASSISTANT.
and f, is the cap of a double-acting pump, the core for which is
shown in section by the white part of Fig. 152 J, the shaded portions
being the metal : the great aperture leads to the piston, the two
smaller are for valves opening inwards and outwards ; this of
course requires a metal core-box capable of division in two parts,
and made exactly to the particular form.
In addition to the cores used for making holes and mortises,
much ingenious -contrivance is displayed in the cores employed
for other works of every-day occurrence, the undercut parts of
which would retain them in the sand but for the employment of
these and analogous contrivances. It will be now readily under-
stood that if, in the Fig. 122, p. 232, the parts shaded obliquely
were separate, there would be no difficulty in removing first the
upper half of the flask, the false cores, after which the patterns
would be quite free. The term false core is employed by the brass-
founder to express the same thing as the drawback of the iron-
founder. The former calls every loose piece of the mould not
intended for holes, a false core. By such a method, however, the
circular edge of a sheave would require at least three such pieces,
but Fig. 153 shows a different way of accomplishing the same
Fig. 153.
thing, when the pattern is made in two parts in the manner repre-
sented.
The entire model is first knocked into the side A, the sand is
cut away to the inner margin of the pattern which terminates
upon the dotted line a, and the side A, of the mould is then well
dusted; a layer of sand is now thrown on, and rammed tolerably
firm to form an annular core, which is made exactly level with the
inner margin b of the pattern, and the core is well dusted ; lastly,
the side B is put on and rammed as usual. To extract the model,
the side B is first lifted, the half pattern b, b, (which is shaded,) is
removed, and the ingate is cut in the side B, to the edge of the
pully ; the mould is well dusted with flour and replaced.
The entire mould is now turned over, A is first removed, then
the remaining half pattern a, a, which must be touched very ten-
derly or it will break down the core; and tfye runner, (which
divides in two branches around the core), is also scooped out in the
side A, which is dusted with flour and replaced, ready for pouring.
Common patterns not requiring cores are frequently divided into
CASTING AND FOUNDING.
249
two parts in the above manner, so that when the mould is open
the pattern may divide and remain half in each side ; this lessens
the risk of breaking down the mould and the attendant trouble oi
afterwards repairing it.
KEVERSING AND FIGURE CASTING. — Supposing that an orna-
ment, represented in section in Fig. 154 has been modeled in relief,
either in clay or wax upon a flat board, from which a thin casting
in brass is wanted without the tablet, the process is called revers-
ing, and is to be accomplished in any of three ways.
First an empty flask is placed upon the board, 154, and rammed
full of sand ; it assumes the appearance of 155 ; the second part
of the flask is attached to 155 and filled to make the part 156,
which is called the back-mould ; some clay is then rolled out to the
intended thickness of the casting, with a cylindrical roller running
on two slips of wood or on two
wires, and a narrow band of this
clay is placed on 156, round the
figure, that it may separate 155
and 156, exactly to the required
distance, ready for receiving the
metal.
By the second mode, 155 is
first made, then 156, and from the
latter 157 is moulded, which is a
counterpart of 155. A thin sheet
of clay is then pressed all over
157, into every cavity, and cut oft*
flush with the plane surface of the mould, by which it assumes the
appearance denoted by the double line in 157. After this 156
is destroyed, and made over 'again in 157, but so much smaller
than before as the thickness of the clay lining ; when the new
back-mould, 156, is placed in contact with 155, it leaves the re-
quired space for the intended casting. This mode is only prefer
able to the first, when many parts of the work are nearly perpen-
dicular; in which case, if the first .mode be adopted, a portion of
the back mould 155 must be pared away at the perpendicular
parts, and if incautiously performed there will be a risk of irregu-
larity of thickness, or even of holes in the casting.
The third mode is to take a casting of 154 in plaster of Paris ;
when this is thoroughly dry it is oiled, and poured full of a cement
of wax, grease, and red-ochre, which is poured out again when par
tially set, leaving a thin crust behind (as in the pewter handle). A
second, a third, or more layers of wax are thus added until the
whole is sufficiently thick, when the wax shell is extracted, and
then moulded from in the ordinary manner ; the first brass casting
is finished and chased to serve as the permanent pattern. The
management of the wax requires practice.
In constructing such moulds additional care is given to every
part of the work ; for example, the sand is sifted much finer, the
250 THE PRACTICAL METAL-WORKER'S ASSISTANT.
parting is made with fine charcoal dust, and the facing with char-
coal and rottenstone mixed together in about equal parts, the mix-
ture being of a slaty color; sometimes the loamstone, which is
found in the pits where clay for making tiles is dug, is "used instead
of rottenstone. The moulds are well dried in an oven, or over the
mouth of the furnace, and the faces are afterwards smoked over a
dull fire of cork shavings ; this deposits a very fine layer of soot
over the face of the mould, which greatly assists the running of
the metal ; when this additional care is taken the works are known
as fine-castings.
In casting figures, such as busts, animals, and ornaments consist-
ing of branches and foliage, considerably more skill is required :
the originals are generally solid, but the moulds necessarily divide
into very many parts. Most persons will have had the opportunity
of judging of the complexity of these moulds, from similar works
in plaster of Paris, which are frequently purchased by artists and
the virtuosi before the seams of the mould are removed.
A glance at these plaster-casts, at the complex and undercut
form of many of these ornamental works, and at the explanatory
diagram on page 231, will convey some notion of the method to
be pursued as well as of the trouble attending them. It is shown
for example, by the diagram just referred to, that all figured
works approaching to the circular or elliptical section, require that
the mould should be divided into at least three parts, except under
most favorable circumstances. In the human figure and quadru-
peds, the four limbs and the trunk require at least three parts each,
and often many more ; it will be easily conceived therefore that
such moulded works require considerable skill and patience.
Piece after piece of the mould is successively produced, just as
in making the core, Fig. 153, p. 248, every piece embracing only
so much of the figure, as in no part to require any core to over-
hang the line in which it is withdrawn. The side of the mould in
which the figure is partly embedded is first dusted with charcoal,
and then the first core is very carefully rammed into the nook,
arid pared down to the new line of division; the green or wet
sand core is then dusted, and the second core is made, and after-
wards dusted, when the moulder proceeds with the third core and
so on ; every one being carefully adapted to its neighbor, and with-
drawn to see that all is right, before the succeeding core is pro-
ceeded with. The relative positions of the cores amongst them-
selves are readily recognized and maintained by the irregularity
of their forms, as in a child's dissected map, or by making a notch
or two here and there, which are faithfully copied in the succeed-
ing piece. It is frequently necessary to thrust two or more broken
needles through the green cores into the neighboring parts to con-
nect them together, in imitation of the pins in the flasks.
All the parts of the mould are dried in the o'ven, and the facings
are smoked over a cork fire as before explained ; the perfection of
the casting is augmented by pouring whilst the mould is still
CASTING AND FOUNDING. 251
slightly warm, as otherwise on cooling it has an increased affinity
for damp ; but the mould when hot is more or less filled with
aqueous vapor, which is equally prejudicial.
When a figure, such as a bust, is required to be cast hollow from
a solid model, it is first moulded exactly as above. The core is
now produced as follows : at the foot of the bust a large space,
nearly equal in length and bulk to the bust, is cut away in the sand,
to serve for fixing the core in the mould, or for the balance, as it is
called, as the core cannot be propped up at both ends. The entire
hollow, that is for the bust and the balance, is filled with a com-
position of about one part of plaster of Paris and two of sand or
fine brick-dust, mixed with a little water and poured in fluid, a few
wires being placed amidst the same for additional support.
The mould is now taken to pieces to extract the core, which is
then dried, thoroughly burned, and allowed to cool slowly (which
the founder calls annealing, from a similar method being employed
in annealing or softening the metals and glass) : the core is then re-
turned to the mould, to see that it has not become distorted. If
needful the fitting around the balance is made good to suit the re-
duced magnitude of the core, which latter is then so far pared away
as to leave room for the thickness of metal ; this is frequently regu-
lated by boring holes at many parts of the core with a stop-drill,
having a collar to prevent its penetrating beyond the determined
depth ; the surface of the core is now pared down to the bottoms
of the holes, as uniformly as possible. When the mould has been
faced, dried and smoked, the whole is put together for pouring, for
which purpose the figure is inverted and filled from the pedestal.
Equestrian and other figures are sometimes cast in two, three, or
more pieces, and joined together by solder, screws, or wires ; but in
all such works, the aim of the founder is to leave little or nothing
for the finisher or chaser to do.
Some objects which are either exceedingly complex in their
form, or soft and flexible in their substance, and which do not
therefore admit of being moulded in sand, in the ordinary manner
of figure casting, may be moulded for a single copy, provided the
originals consist of substances which may be either readily melted
or burned into ashes.
A cavity is made in the sand of the moulding-trough, a little
larger and longer than the object, or else a wooden box of appro-
priate size is procured, in the midst of which the wax model may
be placed ; to the end of the model is added a piece to represent
the runner, which will be required for introducing the metal. The
composition of one-third plaster of Paris and two-thirds brick-dust,
mixed with water, the same as for the core of the bust, is then
poured in. entirely to surround the model. The mould is first
slowly dried, it is then inverted and made warm to allow the wax
to run out, after which it is annealed, or burned to redness, and
lastly, when cooled, it is buried in sand and filled with metal. The
252 THE PRACTICAL METAL-WORKERS ASSISTANT.
method necessarily throws the chance of success upon a single trial,
as the model is destroyed.
Should the face of the casting be required to be particularly
smooth, a small quantity of brick-dust is washed, (in the manner
practised with emery, and to be explained,) and mixed with very
fine plaster : a coat of this is brushed over the model, which ex
eludes air-bubbles, the model is quickly placed in its cavity, and
the coarser mixture is poured in as before.
The above method exactly corroborates a mode long since des-
cribed as being suitable to casting copies of small animals or in-
sects, parts of vegetables and similar objects ; these are to be fixed
in the centre of a small box, by means of a few threads attached to
any convenient parts, one or two wires being added to make air-
holes, and ingates for the metal. A small quantity of river silt or
mud, which had been carefully washed, was first thrown in and
spread around the object by swinging the box about ; and when
partly dry, successive but coarser coats were thrown in, so as ulti-
mately to fill up the box. When it had become thoroughly dry,
the wires were first removed from the earthy mould ; it was then
burned to reduce the object to ashes, and when every particle of
the model had been blown out, it was ready to be filled with
metal.
FILLING THE MOULDS. — Having traced the formation of various
kinds of moulds for brass work, we must now return to the fur-
nace to see if the metal is in condition to be poured, which is in-
dicated by the slight wasting of the zinc from its surface with a
lambent flame. When this condition is observed, the large cokes
are first removed from the mouth of the pot, and a long pair of
crucible tongs are thrust down beside the same to embrace it
securely, after which a coupler is dropped upon the handles of the
tongs : the pot is now lifted out with both hands and carried to
the skimming-place, where the loose dross is skimmed oft' with
an iron rod, and the pot is rested upon the spill-trough, against
or upon which the flasks are arranged.
The temperature at which the metal is poured must be propor-
tione'd to the magnitude of the works: thus large, straggling, and
thin castings require the metal to be very hot, otherwise it will be
chilled from coming in contact with the extended surface of sand
before having entirely filled- the mould ; thick massive castings if
filled with such hot metal would be sand-burned, as the long con-
tinuance of the heat would destroy the face of the mould before
the metal would be solidified.
The line of policy seems therefore to be, to pour the metals at
that period when they shall be sufficiently fluid to fill the moulds
perfectly and produce distinct and sharp impressions, but that the
metal shall become externally congealed as soon as possible after-
wards.
For slight moulds the carbonaceous facings, whether meal-dust-
charcoal, or soot, are good, as these substances are bad conductors,
*/'*..
CASTING AND FOUNDING. ^ / • 253 /
f i " ' / ^
of heat, and rather aid tlian otherwise by their ignition ; it is'a^^,
proper to air these moulds for thin works, or slightly warm them / *
before a grate containing a coke fire. But in massive works these
precautions are less required ; and the facing of common brick-/' t
dust, which is incombustible and more binding, succeeds better. .
The founder therefore fills the moulds having the slightest works
first, and gradually proceeds to the heaviest ; if needful he will
wait a little to cool the metal, or will effect the same purpose by
stirring it with one of the ridges or waste runners, which thereby
becomes partially melted. He judges of the temperature of the
melted brass, principally by the eye, as when out of the furnace
and very hot, the surface emits a brilliant bluish white flame, and
gives off clouds of the white oxide of zinc, a considerable portion
of which floats in the air like snow, the light decreases with the
temperature, and but little zinc is then fumed away.
Gun-metal and pot-metal do not flare away in the manner of
brass, the tin and lead being far less volatile than zinc ; neither
should they be poured so hot or fluid as yellow brass, or they will
become sand-burned in a greater degree, or rather the tin and lead
will strike to the surface, as noticed at page 212. Gun-metal and
the much used alloys of copper, tin, and zinc, are sometimes mixed
at the time of pouring ; the alloy of lead and copper is never so
treated, but always contains old metal, and copper is seldom cast
alone, but a trifling portion of zinc is added to it, otherwise the
work becomes nearly full of little air-bubbles throughout its surface.
When the founder is in doubt as to the quality of the metal,
from its containing old metal of unknown character, or that he
desires to be very exact, he will either pour a sample from the pot
into an ingot mould, or extract a little with a long rod terminating
in a spoon heated to redness. The lump is cooled and tried with
the file, saw, hammer, or drill, to learn its quality.
The engraved cylinders for calico-printing are required to be of
pure copper, and their unsoundness when cast in the usual way,
was found to be so serious an evil that it gave rise to casting the
metals under pressure.
Some persons judge of the heat proper for pouring, by apply-
ing the skimmer to the surface of the metal; which when very hot
has a motion like that of boiling water; this dies away and be-
comes more languid as the metal cools. Many works are spoiled
from being poured too hot, and the management of the heat is
much more difficult when the quantity of metal is small.
The mixture and temperature of the metal being found to be
proper, it is poured in the manner represented in Fig. 119, p. 221 .
the tongs are gradually lowered from the shoulder down the left
arm, and the right hand is employed in keeping back the dross
from the lip of the melting-pot. 'A crucible containing the gen-
'eral quantity of 40 or 50 Ibs. of metal, can be very conveniently
managed by one individual, but for larger quantities, sometimes,
amounting to one hundred weight, an assistant aids in supportiug
254 THE PRACTICAL METAL-WORKER'S ASSISTANT.
the crucible, by catching hold of the shoulder of the tongs with a
grimier, an iron rod bent like a hook.
Whilst the mould is being filled, there is a rushing or hissing
sound from the flow of the metal and the escape of the air ; the
effect is less violent where there are two or more passages, as in
heavy pieces, and then the jet can be kept entirely full, which is
desirable. Immediately after the mould is filled, there are gener
ally small but harmless explosions of the gases, which escape
through the seams of the mould ; they ignite from the runners,
and burn quietly ; but when the metal blows, from the after-escape
of any confined air, it makes a gurgling bubbling noise, like the
boiling of water, but much louder, and it will sometimes throw
the fluid metal out of the runner in three or four separate spirts :
this effect, which mostly spoils the castings, is much the most
likely to occur with cored works, and with such as are rammed in-
less judiciously hard, without being, like the moulds for fine cast-
ings, subsequently well dried.
The moulds are generally opened before the castings are cold,
and the founder's duty is ended when he has sawn off the ingates
or ridges, and filed away the ragged edges where the metal has
entered the seams of the mould ; small works are additionally
cleaned in a rumble, or revolving cask, where they soon scrub each
other clean.
Nearly all small brass works are poured vertically, and the run-
ners must be proportioned to the size of the castings, that they
may serve to fill the mould quickly, and supply at the top a mass
of still fluid metal, to serve as a head or pressure for compressing
that which is beneath, to increase the density and soundness of the
casting. Most large works in brass, and the greater part of those
in iron, are moulded and poured horizontally.
IRON-FOUNDERS' FLASKS, AND SAND MOULDS.— The process of
moulding works in sand is essentially the same both for brass and
iron castings ; but the very great magnitude of many of the latter
gives rise to several differences in the methods: it will suffice,
however, to advert to the more important points in which the two
practices differ, or to those which have not been already noticed ; I
shall therefore commence with a few remarks upon the flasks and
the sand.
In the greater number of cases the iron-founder moulds and
casts his work horizontally, with the flasks lying upon the ground ;
frequently the top part only is lifted ; and in the largest works the
lower part of the flask is altogether omitted, such pieces being
moulded in the sand constituting the floor of the foundry ; in these
cases the position of the upper flask is denoted by driving a few
iron stakes into the earth, in contact with the internal angles of the
lugs, or projecting ears of the flasks.
The sand would drop out of such large flasks,' if only supported
around the margin ; they are consequently made with cross-bars or
wooden stays a few inches asunder, which, unless the entire flask is
CASTING AND FOUNDING. 255
made of wood, are fixed by little fillets cast in the solid with the
sides of the iron flasks. A great number of hooks in the form of
the letter S, but less crooked at the ends, are driven into the bars,
and both the bars and hooks are wetted with thick clay water, so
that the sand becomes entangled amidst them, and is sustained when
the flask is lifted. Some flasks require the force of either two or
several men, who raise them up by iron pins or handles projecting
from the sides of the flask ; they are then placed upon one edge,
and allowed to rest against any convenient support whilst they are
repaired, or they are sustained by a prop.
The very heavy flasks are lifted with the crane, by means of a
transverse beam and two long hangers, called clutches, which take
hold of two gudgeons in the centres of the ends of the flask ; it can
be then turned round in the slings, just the same as a dressing- glass,
to enable it to be repaired.
The modern iron-founder's flasks are entirely of iron, and do not
require the wooden stays, as they are made full of cross ribs nearly
as deep as the flask itself, and which divide its entire surface into
compartments four or five inches wide, and one to two feet long.
On the sides of every compartment are little fillets, sloping opposite
ways, so as to lock in the small bodies of sand very effectually.
When these top flasks are placed upon middle flasks without ribs,
as in moulding thick objects, the two parts are cottered or keyed
together, by transverse wedges fixed in the steady pins of the flask ;
lifters or gaggers are then placed amidst the sand ; these are light
T shaped pieces of iron, wetted and placed head downwards, the
tails of which are largest at top, so as to hold themselves in the
sand, the same as the key-stone of an arch is supported. The gag-
gers are placed at various parts to combine the sand in the two
flasks, and they fulfil the same end as the iron hooks and nails
driven into the wooden stays of the old-fashioned flasks.
The bottom flask or drag has sometimes plain flat cross-ribs two
inches wide (like a flat bottom with square holes), that it may be
turned over without a bottom board ; and unless the flasks have
swivels for the crane, they have two cast-iron pins at each end, and
one or more large wrought-iron handles at each side, by which
they may be lifted and turned over by a proportionate number of
men.
The sand of the iron-founder is coarser and less adhesive than
that used by the brass-founder. The parting sand is the burned
sand which is scraped off the castings ; it loses its sharp, crystal-
line character from being exposed to the red heat. The facing-
sand is sometimes only about equal parts of coal-dust and charcoal-
dust, ground very fine ; at other times, either old or new sand ib
added, and for large thick works a little road-drift is introduced.
All these substances get largely mixed with the sand of the floor,
and lessen its binding quality, which is compensated for by occa-
sional additions of new sand, and by using more moisture with the
sand ; as before extracting the patterns, the iron-founder wets the
256
edges of the sand with a sponge, which has sometimes a nail tied
to it to direct the water in a fine stream ; for heavy works a water-
ing pot is used.
The green-sand moulds are made, as in the brass-foundry, of tho
ordinary stock of old moist sand ; these are often filled as soon as
they have been made.
The dry -sand moulds are made in the same manner, but with
new sand containing its full proportion of loam ; these moulds are
thoroughly dried in a large oven or stove, and then black-washed
or painted with thin clay water containing finely ground charcoal ;
this facing is also thoroughly dried before the moulds are poured.
The loam moulds, which are much used for iron castings and
somewhat also for those of brass, are made of wet loam with a little
sand, ground together in a mill to the consistence of mortar ; the
moulds are made partly after the manner of the bricklayer- and
plasterer, as will be explained ; the loam moulds also are thoroughly
dried, black- washed, and again dried, as from their greater com-
pactness they allow less efficient escape for the vapor or air, and
therefore they must be put into the condition not to generate much
vapor when they are filled.
Iron moulds are also employed for a small proportional number
of works which are then called chilled castings ; these were referred
to at pages 163 and 164 ; and occasionally the methods of sand cast-
ing and chilling are combined, as in some axletree-boxes, which are
moulded from wooden patterns in sand, and are cast upon an iron
core. To form the annular recess for oil, a ring of sand, made in
an appropriate core-box, is slipped upon the iron mandrel, and is
left behind when the latter is driven out of the casting.
It would be a useless repetition to enter into the details of mould-
ing ordinary iron works; but from the horizontal position of the
flasks it is necessary that the part of the work which is required to
be the soundest, and most free from defects, should be placed down-
wards, as the metal is more condensed at the lower part, and free
from the scoria or sullage which sometimes renders the upper sur-
face very rough and full of minute holes. As the flasks almost
always lie on the ground, it is also found the most convenient to
retain them in contact by placing heavy weights upon them ; the
foundry should in consequence have an abundant supply of these.
The flasks require to be poured through a hole in the upper
half, as seen at r, Fig. 169, page 259, which hole is formed by
placing a wooden runner stick in the top part A, whilst it is being
rammed ; and a small channel is afterwards cut sideways into the
mould. Sometimes two, three, or even half-a-dozen or more run-
ners are put to one single casting, either when it requires a great
weight of metal, or when it is large but slight, as in trellis- work,
in which case the metal might cool before filling the mould if only
introduced at one single runner.
When the runners are required to be lofty, either to supply pres-
sure to the metal, or as a reserve to fill up the space left by its con-
CASTING AND FOUNDING.
257
traction in cooling, iron rings of six or eight inches diameter are
piled up to the required height, to support the tube of sand con-
tained within them. Small objects that are poured from one hole,
are frequently moulded with two runners, that the metal may flow
through the mould, and that there may be a sufficient supply to
meet the shrinkage, and also to supply head or pressure ; another
advantage also results, as it assists in carrying off the scoria or
milage. t
The iron-founder employs all the methods of coring explained at
Eages 245 to 248, and also others of an entirely different kind but
ttle required in brass- works ; namely for lateral holes in the parts
of the castings buried beneath the general surface of the mould,
and which are explained by the Figs. 158 to 161. Thus 158 repre-
sents the finished casting, 159 the model of the same, 160 the ap-
pearance of the bottom flask or drag when the pattern is first re-
moved, and 161 the flask and cores when closed ready for pouring ;
the moulds are inverted, and the same letters of reference refer to
similar parts of all these figures.
Figs. 158
160
161. 6
The core print a, would deliver from the sand and leave the
cavity at a, Fig. 160, to be afterwards filled by the core shown
black in Fig. 161, the same as formerly explained at Fig. 143, p.
245. But the core print, b, Fig. 159, (which has reference to the
black stud b, Fig. 161,) would tear away the sand above it in with-
drawing the pattern ; therefore the print I should, like d, Fig. 159,
extend to the face of the pattern, or the parting line represented by
e, Fig. 161. This being the case, the pattern would leave the space
denoted at d, Fig. 160 ; the core is put down sideways to the bot-
tom of the recess, and extends entirely across the same ; the small
open space above, is made good with the general surface, as shown
by the shade lines in Fig. 161, and this filling in at the same time
fixes the core precisely where denoted by the print d, which latter
has a mark to show to the moulder where the core is to end. The
circular hole requires the core print shown at c, Fig. 159 ; the cores
themselves are made in the core-boxes 144 and 145, before ex-
plained at page 246.
Fig. 163 represents the model and core-print, from which the
finished casting shown at Fig. 162 might be made from a solid pat
tern in a two-part flask ; it would be inverted, and the parting
would be made upon the line, x. The prints for the four holes a a,
would be placed in the top flask, and those for the great apertures
or panels d, would be made in a core-box of the express form, and
258
THE PRACTICAL METAL-WORKERS ASSISTANT
as thick as the pattern and core-print measured together. The
core would be deposited edgeways into the core-print, and the
upper corners of the mould would be made good, as explained in
Fig. 161.
Figs. 162
163
By the same method, a mortise wheel, or one with spaces around
its edge, as at ra ra, Fig. 164, to be filled with wooden cogs, might
be made with a series of core-prints, as at c, brought up flush with
the parting of the mould ; if every print were filled with a core such
as Fig. 165, made in an appropriate core-box, the matter would be
accomplished with great facility and truth.
The iron-founder makes frequent use of flasks, which divide in
three or four parts ; this is done in many cases simply to increase
the depth of the contained space ; in which case when wooden flasks
were employed, they admitted of being temporarily fixed together
by dogs, or large iron staples, driven a little way into the neighbor-
ing flasks, but the modern iron flasks are fixed by cotters. The
following examples will show the nature of some other uses to
which the flasks with several partings are applied.
Fig. 166.
Fig. 167.
A casting, such as Fig. 166, which represents the top of a sliding-
rest for a lathe, might be moulded in a very deep two-part flask, if
the parting were made upon the dotted line a, a ; but there would
be very great risk of tearing down the mould 'in drawing out the
pattern, and from the depth, there would be scarcely a possibility
of repairing it, and the metal would probably be strained. It would
CASTING AND FOUNDING.
259
be also possible to mould it with the joining upon the line b, pro-
vided several cores were employed, but the mode adopted is more
convenient than either of these — when the pattern is made in two
parts, and the flask in three, as in Fig. 167.
A and B are first united and partly filled with sand, the pattern
is knocked in as represented, and the whole well rammed, especi-
ally in the groove, the parting being made on the line, 1, 1, and
dusted. C is now put on, filled, and struck off level, a board is
put above it, and ABC are all turned over together, A becoming
the top.
A is now removed, and the sand is cut away to make the second
parting on the line 2, 2, after which A is replaced, and the run-
ner-stick is inserted to make the runner, r. On removing the pat-
tern, the runner-stick r is first taken out, A, or the top part of the
flask, is lifted off, and the white part of the pattern is drawn out ;
B, or the middle part, is then lifted, and the last or shaded piece
of the pattern, is drawn out of the mould, which is now put to-
gether again, and poured through r] so that the top surface of the
pattern, as seen in both views, becomes the face, from being cast
downwards, or upon the lowest piece C, of the flask, called the
drag.
The part c, Fig. 166, might be cast with a chamfer in three dif-
ferent ways ; although, in small castings, it is more usual to cast it
square and plane it out of the solid. First, the pattern might be
moulded square, and the top A, after removal, might be worked to
the angle by aid of the trowel and a chamfered slip of wood, used
as a gage ; or secondly, by the employment of a core, the print of
which is represented by the dotted lines terminating at the angle d,
Fig. 166 ; or thirdly, by having a loose slip on the pattern sliding
on the line c, Fig. 166, so as to be drawn off when the top A, had
been lifted. This last method is analogous to that represented in
Fig. 168, also intended for a sliding-rest • and which might be cast
Fig. 168.
Fig. 169.
in a two part flask, if the two camfers c c, were fitted loosely upon
slides as shown; but a three-part flask is more convenient, as ex-
plained by Fig. 169, in which the pattern is inverted.
260 THE PRACTICAL METAL-CORKER'S ASSISTANT.
The lowest piece C, or the drag, is parted upon the line 1, 1, but
its sand extends upwards between the two sides of the pattern, as
shown by the shade-lines. The middle piece B, is parted through
the line 2 2 ; and lastly A. the top, is filled up level, the runner-
stick at r being inserted at the time, A is first lifted, and all the
pattern is then removed, excepting the chamfered bars and their
slides, which are represented black ; this pattern delivers its own
cores for the circular mortises m m, the sand forming them being
a part of that in B, or the middle flask ; lastly, B is lifted, and
chamfer-slips are picked off from C. This pattern may conse-
quently be moulded without turning over the flask, and every part
of the mould is quite accessible for repair.
The pedestal of the swage-block, Fig. 95, page 141, is another
good example of moulding in a three-part flask. The model is
' made with the upper fillet loose, also with the sides solid, or with-
out the holes, and the object is moulded as it stands. The top part
of the flask opens at the upper moulding, and which latter is then
removed from the pattern ; the middle flask divides at the plinth
or flange, so that when this has been lifted, the pattern also may
be withdrawn, leaving a square pedestal of sand, as large as the
interior of the model, standing upon the bottom part or drag, as in
169. The panels are made by means of a core-box of the kind
Fig. 146, p. 246, the box is exactly as thick as the metal to be
cast ; and the circular cores are then fixed upon the pedestal of
sand by means of a few wires or nails, after which the fla-sk is put
together, ready for pouring.
If the Fig. 95, here referred to, had four fluted columns at the
four angles, either with a large cap to each, or with a square entab-
lature connecting the whole of them, the object might be also cast
in one piece, if moulded in a three-part flask. After removing the
top flask, the entablature and capitals would be first withdrawn, the
columns being divided through their smallest diameters ; the mould
would be then turned over, and upon lifting off the drag, or bot-
tom-piece, the remainder of the pattern could be drawn, either in
one single piece, or if the pillars were loose, the five parts could be
more safely extracted ; the three-part mould would be put together
again and reversed for pouring. In this general manner, by mak-
ing either the mould, or the pattern, or both, in different pieces,
and by the judicious employment of cores and drawbacks, objects
apparently the most untractable are cast with very great perfection.
The iron-founders are likewise very dexterous in making cast-
ings in some respects different from the patterns from which they
are moulded ; thus, if the pattern be too long, or that it be tem-
porarily desired to obliterate some few parts, the mould is made of
the full size and stopped-off, additional sand being worked into the
mould by aid of the trowel and some temporary piece of wood to
represent the imagined termination of the pattern. On the other
hand, any simple enlargement or addition is not always added to
CASTING AND FOUNDING. . 261
the pattern, but it is frequently cut out of the mould with the
trowel, in a similar manner.
Many common works, such as plates, gratings, parts of ordinary
stoves, and simple objects, are made to written measures, and with-
out patterns, as a few parallel slips of wood to represent the margin
of the casting, are arranged for the purpose upon a flat body of.
sand, which is modelled up almost entirely by hand ; but for all
accurate purposes and for machinery, good and well-made patterns
are indispensable, and to some particulars of which a little atten-
tion will be now devoted.
KEMARKS ON PATTERNS FOR IRON CASTINGS. — The construc-
tion of patterns for iron castings requires not only the observance
of all the particulars conveyed on pages 238 to 240, but, in ad-
dition, the large size of the models, the peculiar methods employed
in moulding them, and the nearly inflexible nature of the iron cast-
ings when produced, call for some other and important considera-
tions,— and which should not be entirely overlooked, even in works
of comparatively small size, or it may lead to failure and disap-
pointment.
Thus, it becomes necessary to make patterns in some degree
larger than the intended iron castings, to allow for their contraction
in cooling, which equals from about the ninety-fifth to the ninety-
eighth part of their length, or nearly one per cent. This allowance
is very easily and correctlv managed by the employment of a con-
traction rule, which is made like a surveyor's rod, but one-eighth
of an inch longer in every foot than ordinary standard measure.
By the employment of such contraction rules, every measurement
of the pattern is made proportionally larger without any trouble
of calculation.
When a wood pattern is made, from which .an iron pattern is to
be cast, the latter being intended to serve as the permanent foundry
pattern, as there are two shrinkages to allow for, a double contrac-
tion rule is employed, or one the length of which is one-quarter of
an inch in excess of every foot. These rules are particularly im-
portant in setting out alterations in, or additions to, existing ma-
chinery. The latter is measured with the common rule, and the
new patterns are set out, to the same nominal measures, with a
single or double contraction rule, as the case may be, the three
being made in some respects dissimilar to avoid confusion in their
use. The entire neglect of contraction rules incurs additional
trouble and uncertainty. The contraction of brass is nearly three-
sixteenths of an inch in every foot, but from the small size of
brass castings the contraction rule is less required for them, as the
differences may be easily allowed for without it.
Iron castings weigh about fourteen times as much as the ordi-
nary deal and fir patterns from which they are made, that being
nearly the ratio of the specific gravities of those materials.
Patterns for iron castings are much more frequently divided into
several parts than those for brass. For instance, the division into
262 THE PRACTICAL
two equal parts, after the manner of Fig. 153, p. 248 (but without
reference to the under-cutting) is very common, as both the pattern
and flask separate when the top part is lifted, and the halves of the
pattern can then be drawn out from the halves of the flask with
much less risk of tearing down the sand.
Keferring to p. 232, Fig. 122 if small, would be moulded as rep-
resented, with false cores or drawbacks ; but if it were a large
fluted column, the iron-founder would employ a solid two-part
flask ; the shaded parts would together represent the body of sand
in the drag, and the pattern would be made in three parts some-
thing like a boot-tree. When the top flask had been lifted, the
central slice of the pattern, extending from the two upper to the
two lower angles, would be withdrawn vertically, and the two outer
pieces would be released sideways. The general rule is to divide
the circumference of the pattern into six equal parts, and to let the
central slice equal one of them in width.
The Figs. 167 and 169, representing two parts of a slide-rest,
and the pedestal, 95, are some amongst many of the common ex-
amples of the division of the patterns ; and with which may be
associated, the numerous subdivisions of the mould instead of the
pattern by the employment of cores, many applications of which
have been also explained. All these matters display much in-
teresting and ingenious contrivance, resorted to either to render pos-
sible the operation of moulding, or to facilitate its performance.
To lessen the distortion of castings from their unequal contrac-
tion in cooling, it is important that the models should be nearly
symmetrical. For example, bars or rods of all the sections in
Fig. 121, p. 232, may be expected to remain straight; perhaps g
is the most uncertain, but if the lower fins of e and h were removed,
their flat surfaces, then exposed to the sand, would become round-
ing or convex in length, from the contraction of the upper rib
being unopposed by that of a similar piece on the under side.
Bars and beams, the sections of which resemble the letter I, are of
the most favorable kind for general permanence, and also for
strength, and large panels may be cut out from their central plates
to diminish their weight without materially reducing their stability.
They are much used, not only in building, but also in the framing
of machinery, which is in a great measure based upon the same
general rules.
It is also of great importance, especially in castings of large
size, that the thickness of the metal should be nearly alike through-
out, so that it may cool at all parts in about the same time. Should
it happen that one part is set or rigid, whilst another is semi-fluid
or in the act of crystallizing, there is great risk of the one part
being altogether torn from the other and producing fracture. Or
should the disturbing force be insufficient to break the casting, it
may strain the metal nearly to its limit of tenacity or elasticity ;
so that a force far below that which the casting shoul<J. properly
bear may break it in pieces.
CASTING AND FOUNDING. 263
An example of this is seen in wheels with very light arms and
heavy rims or bosses. The arms sometimes cool so quickly as to
tear themselves away from the still hot rim or nave ; or when the
arms are solidified without fracture, the contraction of the rim may
so compress the spokes endways as to dish the wheel (in the man-
ner of an ordinary carriage wheel), and thereby strain the casting
nearly or quite to the point of fracture. The arms are sometimes
curved like the letter S, instead of being straight and radial ; the
contraction then increases their curvature with less risk of accident
than to straight arms. It appears to be often desirable to super-
sede the straight diagonal braces of iron castings by curved lines,
which are both more ornamental and better disposed to yield
to compression or extension by a slight alteration in their cur-
vature.
A more elegant way of avoiding the mischief is by placing the
spokes as tangents to the central boss, in which case the contraction
of the rim makes a small angular change of position in the boss ;
for the rim, in thrusting the spokes inwards, causes the boss to twist
round a little way with far less risk of fracture.
The destructive irregularity of thick and thin works is partly
averted by uncovering the thick parts of the casting, or even cool-
ing them still more hastily, by throwing on water from watering-
pots. In wheels this has been done by a hose, the axis of which
is concentric with the wheel, the arms being all the time sur-
rounded by the sand to retard their cooling ; but it is the most
judicious in all patterns to make the substance for the metal as
nearly uniform throughout as circumstances will admit, so as not
to require these modes of partial treatment, which often compro-
mise the ultimate strength of the casting.
Another mode sometimes adopted for avoiding the fracture of
wheels, from the great dissimilarity of their proportions, is by in-
serting wrought-iron arms in the mould, but they do not always
unite kindly with the iron of the rim and the nave. The same in-
convenience occurs when iron pins are inserted in the ends of
either iron or brass castings, to serve for their attachment to their
respective places. In iron castings it frequently produces the effect
of chill casting, so as to render the works difficult to be turned or
filed at the junction, and there is risk of the casting becoming
blown or unsound in either case. When the pins are heated before
being placed in the mould, they become nearly cold before the
metal can be poured, and they also endanger the presence of a little
steam or vapor, which is detrimental ; therefore they are more
generally put in cold, notwithstanding the sudden check they then
give to the fluid metal. ^
The patterns for iron castings of large size are necessarily very
expensive, especially those for hollow cylinders and pans, many of
which are so large that it would be impossible to find solid pieces
of wood from which the patterns could be made, either with
sufficient strength for present use, or with the necessary perma-
2G4
THE PRACTICAL METAL-WORKERS ASSISTANT.
nence of form for a subsequent period, as they would be almost
sure either to break or to become distorted from* the effects of
unequal shrinking. Such patterns, therefore, require to be made
of a great many thin layers or rings of wood, each consisting of
6, 8, or 12 pieces, like the felloes of wheels, so that in all parts the
grain may be nearly in the direction of a tangent.
As they are glued up, every succeeding layer is connected with
the former by glue and wooden pins or dowels, and the whole is
afterwards turned to the tubular or hemispherical form, as the case
may be. As the castings are generally required to be rather thin,
such models are not only very expensive, but also very liable to
accident ; and besides, it frequently occurs that only one or two
castings of a kind may be required, which makes the proportional
cost of the patterns excessive.
It fortunately happens, however, that this case, which is one of
the most costly and uncertain, by the employment of ordinary
wood or metal patterns, becomes exceedingly manageable by a
peculiar and simpfe application of the art of turning (the one great
centre of the constructive arts, to which these pages are intended
immediately and collaterally to apply) ; and by which process, or
one branch of loam moulding, to be explained hereafter, patterns
are1 not generally required.
LOAM MOULDING. — Figs. 170, 171, and 172, are intended to
illustrate this process as regards a steam cylinder. Fig. 170 is the
Figs. 170
171
entire section of the mould in its first stage. Figs. 171 and 172
are the half sections of the second and third stages, preparatory to
burying the mould in the pit in which it is to be filled,
j The inner part of the loam mould is called the core when small,
but the nowel when large ; the outer is called the case or the cope.
Each part is built upon an iron loam-plate, or a ring cast rough on
the face, and with four ears by which it may be lifted. The mould
is occasionally erected upon four shallow pedestals of bricks for
the convenience of making a fire beneath it to dry the loam. At
CASTING AND FOUNDING. 265
other times it is made upon a low truck, upon which it may be
wheeled into the loam stove, which is heated to about the tempera-
ture of 300 to 400 degrees Fahrenheit.
A vertical axis a, is mounted in any convenient mannQr, fre-
quently in two holes in the truck itself, or as shown in the figure,
in a pedestal or socket erected upon the truck ; at the other times
the axis is mounted in a hole in the loam-plate, and in any bear-
ing attached either to the building or its roof.
The first step is to fix upon the spindle, the templet b b, at the
distance of the radius of the cylinder, either by one or two clutches
with various binding screws. An inner cylinder of brickwork is
then built up, plastered by the hands with soft loam (which is re-
presented black in all figures), and scraped into the cylindrical
form by the radius board, which is moved round on its axis by a
boy. When the surface is smooth and fair it is thoroughly dried,
after which it is brushed over with blackwash, and again dried.
The charcoal dust in the blackwash serves as a parting, to prevent
the succeeding portions of the loam- mould from adhering to the
first.
The templet c c, Fig. 171, cut exactly to the external form of the
cylinder, is now attached to the axis at the distance from the core
required for the thickness of the metal : some additional loam is
thrown on to form the thickness, which is smoothed in the same
careful mariner as the centre, after which the templet and spindle
are dismounted, and the thickness, which is represented white in
Figs. 171 and 172, is also dried and blackwashed.
The ring for the outer case or cope is now laid down, and its
position is denoted either by fixed studs or by marks ; and the
outer case represented in Fig. 172 is built up of bricks and loam,
with an inner facing of loam worked very accurately to the turned
thickness. The new work or the cope, is also thoroughly dried,
and afterwards lifted off very carefully by means of the crane and
a cross beam with four chains. This process likewise drags off
the thickness, which usually breaks in the removal ; its remains
are carefully picked out of the cope, both parts of the mould are
repaired, and again blackwashed and dried.
When the cylinder requires ports at the ends, or the short tubes
with flanges for attaching the steam-passages, models of the tubes
are worked into the cope, and are afterwards withdrawn ; the cores
are made in core boxes, and are partly supported by the outer ex-
tremity, and partly upon grains, or two little plates of sheet iron
connected by a central wire, the whole being equal to the thick-
ness of the metal at the part. When steam-passages, are wanted,
either along the side, or around the cylinder, they are worked up
in clay upon the thickness, and duly covered in by the cope ; their
cores are supported, partly by their loose ends, and partly by
grains, which become entirely surrounded by, and fixed in the
metal, when it is poured.
There is always some uncertainty of the sound union of the
266 THE PRACTICAL METAL- WORKER'S ASSISTANT.
grains, or other pieces of iron, with the cast-metal. Some cast
them in iron and file them quite bright, others also tin them, ap-
parently to preserve them from rust, as the tin must be instantly
dissipated by the hot metal. Grains should always present clean
metallic surfaces, and when used for very thin castings to prevent
them from dropping out, the wires are nicked with a file that they
may be keyed in the metal. It is however better to avoid the use
of grains, which may be generally done by giving the core sand
bearings, and afterwards plugging up the holes in the casting.
The mould is now put together in a pit sunk in the floor of the
foundry, and the two iron plates are screwed together ; the surround-
ing space being rammed hard to prevent the mould from bursting
open, but the inner part is left much more loose for the escape of
the air. The top edges of the mould are covered over with a loam-
cake (which has been previously made and dried), or a ring three
or four inches thick, strengthened with iron bars amidst the clay,
the joining being made air-tight by a little cowsr hair, and by the
pressure of a quantity of iron weights ; the loam-cake is generally
perforated with many holes as shown at d, for the entry of the
metal and the escape of the air. But provision must always be
made in casting thin cylinders, boxes, and such like forms, for the
breaking up of the core as soon as the metal is set, to prevent the
metal scoring or rending from its contraction upon a rigid unyield-
ing centre.
To enable the mould to resist the great pressure of the lofty
column of fluid metal (equal at the base to near 60 pounds on
every square inch), the core is strengthened by diametrical iron
bars entering slightly into the brickwork : the outer cylinder is
surrounded at a small distance by iron rings piled one on the
other, the interval being rammed with sand ; and stays are placed
in all directions from the rings to the sides of the pit, which is
either lined with brick- work, or when liable to be inundated with
water, it is made of iron, like a water-tight caisson.
Small cylinders are moulded in sand from wooden models, and
only the cores are turned in loam ; for cylinders of the smallest
size the cores are made of sand in core boxes as already explained.
Large pans, and various other circular works, are moulded pre-
cisely in the same way as cylinders ; except that curved templets
are used, and that towards the conclusion, the apertures through
which the spindle passed are filled in and worked by hand to the
general surface.
Water-pipes are made much in the same mode, but the cores for
these are turned upon an iron tube pierced full of holes, which is
laid horizontally across two iron trestles with notches, and is kept
in rotation by a winch handle at the end : there is also a shaper-
board or scraper fixed parallel with the axis; this primitive
apparatus is called a founder's lathe.
The perforated tube (serving as the mandrel) is first wound
round with hay-bands, then covered with loam, and the core is
CASTING AND FOUNDING. 267
turned, driqd and blackwashed ; the thickness is now laid on and
also blackwashed, after which the object is moulded in sand. The
thickness is next removed from the core, which latter is inserted
in the mould, and supported therein by the two prints at the extrem-
ities, and by grains with long wires, the positions of which may
be seen by the little bosses on the pipe, the metal being there
made purposely thicker to avoid any accidental leakage at those
parts. When pipes are cast in large quantities, they are moulded
from wooden patterns in halves, so that it only becomes necessary
to turn the core, and this, when made in the above manner, is
sufficiently porous for the escape of the air.
The moulds for crooked pipes and branches are frequently made
in halves, upon a flat iron plate. An iron bar or templet of the
curve required is fixed down, and a semicircular piece of wood,
called a strickle, is used for working and smoothing the half core ;
next a larger strickle is used for laying on the thickness, the two
halves are then fixed together by wires, and moulded from in the
sand flask ; the thickness is now stripped off the core, which is fixed
in the mould by its extremities, and if needful, is supported also
upon grains.
By the employment of these means, although the loam work re-
quires time for the drying, yet with ordinary care an equality of
thickness may be maintained, notwithstanding the complexity of
the outline, and without the necessity for wooden patterns.
Very many of the large works in brass are also moulded in loam,
the management being in most respects exactly the same as for
iron, except that in some ornamental works wax is more or less
employed, and is melted out of the moulds before the entry of the
metal ; a very slight view of the methods will serve as a sequel to
the subject of brass founding.
Large bells are turned in almost the same manner as iron cylin-
ders or pans, by means of wooden templets, edged with metal and
shaped to the inner and outer contour of the core and thickness.
The inscription and ornaments are either impressed within the cope,
the clay of which is partially softened for the purpose, or the orna-
ments are moulded in wax, and fixed on the clay thickness before
making the cope. Less generally the whole exterior face of the
bell, or indeed its entire substance, is modelled in wax, and melted
out before pouring. In any case, the concluding steps in filling up
the apertures where the spindle passed, are to attach a dissected
wooden pattern, of the central stem and of the six cannons or ears
by which the bell is slung, which parts are moulded in soft loam ;
and then, the parts having been dried, and replaced, and the iron
ring for the clapper inserted, the whole is ready for the pouring
pit. The heaviest bells are moulded within the pit the same as
huge cylinders.
Brass guns are also moulded in loam, and in a somewhat peculiar
manner ; a taper rod of wood much longer than the gun, is wound
round with a peculiar kind of soft rope, upon which the loam is put
268 THE PRACTICAL METAL- WORKER'S ASSISTANT.
for making the rough casting model of the gun, which is turned to
a templet ; the work is executed over a long fire to dry it as it
proceeds, and the model is made about one-third longer than the
gun itself. The model when dried and blackwashed all over, is
covered with a shell of loam, not less than three inches thick, secured
by iron bands, the shell is also carefully dried ; after this the taper
bar is cautiously driven out from its small end, the coil of rope is
pulled out, and so likewise is every piece of the clay model of the
gun.
The parts for the cascable and trunnions, which should have
been worked separately upon appropriate wooden models, are then
attached to the shell. Should the gun have dolphins, or any other
ornamental figures, now seldom the case, they are modeled in wax
and fixed on the clay model before the shell is formed, and are then
melted out to make the required space for the metal.
When all is ready and dried, six, eight, or more of these loam
cases, or shells, are sunk perpendicularly in a pit at the mouth of
the reverberatory furnace, and the earth is carefully rammed around
them ; at the same time a vertical runner is made to every mould,
to enter either at the bottom, or not higher than the trunnion : the
upper ends of the runners terminate in the bottom of a long trough
or gutter, at the far end of which is a square hole, to receive the
excess of metal.
In casting brass guns, tapping the furnace is rather a ceremony,
and certainly an imposing sight : the middle and the end of the
trough, are each stopped by a shovel or gate held across the same;
and the runners are all stopped by long iron rods, held by as many
men. When all is pronounced to be ready, the stopper of the fur-
nace is driven inwards with a long heavy bar swung horizontally
by two or three men, and the metal quickly fills the trough ; on
the word of command, " number one, draw" the metal flows into the
first mould, and fills it quickly but quietly from the bottom ; the
mould being open at the top, no air can be accidentally enclosed.
Numbers two, three, and four are successively ordered to draw.
The first shovel is then removed from the great channel, and now
the guns, five to eight or ten, as the case may be, are similarly
poured and filled to the level of the trough ; after which the last
shovel is withdrawn, and the residue of the metal is allowed to run
into the square bed or pit prepared for it. The flow of metal from
the furnace is regulated by the tapping bar, the end of which is
taper, and is thrust more or less into the mouth of the furnace as
required ; the trough and runners are thus kept exactly full, which
is an important point in most cases of pouring, as it prevents a
current of air being carried down along with the metal.
Large bells are poured much in the same manner, except that
the runners are at the top, and the metal runs from the great
channel, through smaller gutters to every sunk'mould, the stoppers
for which are successively drawn. For quantities of brass inter-
mediate between the charge of an ordinary crucible, and such as
CASTING AND FOUNDING. 269
require the reverberators furnace, the large ladles or shanks of the
iron-founder are used ; the contents of four or six crucibles being
poured into the shank as quickly as possible, and thence in one
stream into the mould.
The author of the article Founding, in the Encyclopedia Metropo-
lilana, minutely describes three ways of casting large hollow statues,
which are briefly as follows :
First : a rough model of the figure is made in clay, but somewhat
smaller than its intended size ; it is covered over with wax, which
is modeled to the required form, or the wax is worked up in sep-
arate pieces and afterwards attached : various rods or cylinders of
wax to make the apertures for the runners or air holes, are fixed
about the figure and led upwards. The whole is now surrounded
with a coating of loam and similar materials, the inner portion of
which is ground very fine and laid on with a brush like paint ;
and the outer part is secured with iron bands. When all has been
partially dried a fire is lighted beneath the grating on which the
figure is built, to cause the wax to run out through one or more
apertures at the base, which are afterwards stopped, and all is
thoroughly dried and secured in the pit, after which the charge of
the furnace is let into the cavity left by the wax.
Secondly : the finished figure is modeled in clay, and stuck full
of brass pins just flush with its surface, which surface is now scraped
away as much as the thickness required in the metal ; the reduced
figure is now covered with wax mixed with pitch or rosin, which
is worked to the original size with all the exactness possible. The
other stages are the same as in the foregoing ; the metal studs or
pins prevent the mould and core from falling together, and they
afterwards melt, becoming a part of the metal constituting the
figure.
Thirdly : the finished figure is modeled in plaster, and a piece-
mould is made around it, the blocks of which consist internally of
a layer of sand and loam 1J inch thick, and externally of plaster
one foot thick. The moulcfwhen completed is taken to pieces,
dried, and rebuilt in the casting pit ; it is now poured full of a
composition suitable for the core, the mould is again taken to
pieces, the core is dried and scraped to leave room for the metal,
and all is then put together for the last time, secured in the pit and
the statue is cast.
The first plan is the most wasteful of metal, the third, the least
so, although it is the most costly when the time occupied is also
taken into account ; but it has the advantage of saving the original
work of the artist.
MELTING AND POURING IRON. — Iron is usually melted in a blast
furnace, or as it is more commonly called, a cupola; although the
cupola or dome leading to the chimney, from which it would ap-
pear to have derived its name, is frequently omitted, the two or
three furnaces being often built side by side in the opan foundry.
At the basement there is a pedestal of brickwork about 20 to 30
270 THE PRACTICAL METAL- WORKER'S ASSISTANT.
inches high, upon which stands a cast-iron cylinder from 30 to 40
inches diameter, and 5 to 8 feet high ; this is lined with road-drift,
which contracts its internal diameter to 18 or 2-i inches. The fur-
nace is open at the top for the escape of the flame and gases, and
for the admission of the charge, consisting of pig-iron, waste of old
metal, coke and lime, in due proportion. The lime acts as a flux,
and much assists the fusion ; chalk is considered to answer the best,
but oyster shells are Very commonly used where they are abun-
dant.
At the back of the furnace, there are three or four holes one
above the other for the blast, which is urged by bellows or by a re-
volving fan. No crucible is used, and as the fluid metal collects at
the bottom of the furnace, the blast pipe is successively removed to
a higher hole, and the lower blast hole is stopped with sand, which
partly fuses and secures the blast hole very effectually.
The front aperture of the furnace through which the metal is
allowed to flow into the ladles or trough, is usually made sufficiently
large for the purpose of clearing or raking out rapidly the fuel and
slag, as the process is most laborious owing to the excessive heat.
This aperture is closed by a guard-plate, fixed on by staples attached
to the iron-case of the furnace, in the centre of which plate the
tapping hole is made: during the time the metal is fusing the tap
hole is closed by sand well rammed in, and this if well done is never
found to fail.
Many iron furnaces are made octangular, and in separate parts
bound together by hoops, so that in the event of the charge becom-
ing accidentally solidified in the cupola, the latter may be taken to
pieces for its removal, and thus avoid the necessity of destroying
the furnace. There is frequently a light framing or grating above
the furnace, upon which the small cores are placed that require to
be dried.
In some foundries the cupolas are built just outside the moulding
shop, beneath one or more chimneys or shafts, which carry oft' the
fumes; in such cases the fronts of the furnaces are accessible through
an aperture in the foundry wall, with which they are nearly flush ;
when the furnaces are lofty there is a feeding stage at the back,
from which the charge is thrown in.
For heavy iron castings, which sometimes amount to thirty tons
and upwards in one piece, reverberatory or air furnaces are also
commonly used ; the ordinary charge for these is four to six tons
of iron, and five or six furnaces are commonly built close together, so
that they may be simultaneously tapped in the production of such
enormous works.
For melting iron in the small way, good air furnaces may be
used, and also some of the black-lead furnaces, which are blown
with bellows, but this is one of the processes that is not successful
upon a limited scale.
Considerable judgment is required in proportioning the charge
for the iron furnace, which always consists of at least two, and often
CASTING AXD FOUNDING. 271
of half-a-dozen kinds of new pig-iron mixed together, and to which
new iron a small proportion of old ca^t-iron is usually added. The
kinds and qualities used are greatly influenced by local and other
circumstances, so that nothing can be said beyond a few general
remarks.
When the principal object is to obtain sound castings with a very
smooth face, as for ornamental works not afterwards wrought, the
soft kinds of iron containing most carbon, which are most fusible
and flow easily, are principally used. But such metal would neither
possess sufficient hardness, durability, nor strength, for many of the
castings employed in the construction of edifices and machinery.
If the cupola contained a little hard pig-iron, but were in great
measure filled with the old cast-iron, which had been repeatedly
melted and had become successively harder from the loss of carbon
at every fusion ; such castings would be brittle, and sometimes so
hard as scarcely to admit of being cut ; these would be equally
unfit for the generality of machinery from the opposite causes.
But the same mixture of iron will be found to differ very much
according to the size of the objects in which it is cast. Iron
which in a plate one-fourth of an inch thick may be quite brittle
and hard, will mostly be of good soft and useful quality in a stout
bar or plate of two or three inches thick. Thick castings are
necessarily slow in cooling, and are seldom very hard unless in-
tentionally made so.
Between the extremes (say three parts of pig-iron to one of old,
or three parts of old iron to one of pig-iron), various qualities may
be selected. In castings for machinery the general aim is to obtain
a strong, sound, and tough iron. Mixtures of this nature which are
used for iron ordnance are called gun -metal amongst the gun-founders.
The fireman, or the individual having the management of the
furnace, therefore always employs the scales in mingling the dif
ferent kinds of iron, according to the magnitude and character of
the works to be cast ; and until the sorts in use are familiarly
known, it is partly a matter of trial, and requires the same atten-
tion as the making of alloys, properly so considered.
It is much to be regretted that no protection has yet been found
to prevent the conversion of cast-iron into plumbago, or the car-
buret of iron, from long immersion in sea- water, or the water of
copper mines, sewers, and other places. This, which is a most
serious inconvenience in dock works, sea walls and mines, arises,
says Dr. Michael Faraday, from the circumstance that the protoxide
of iron, formed beneath salt water, is soluble, and becomes washed
away, thus robbing the original mass of its iron ; whereas the
peroxide, or ordinary rust formed by exposure to the air, is in-
soluble, and serves partly as a defence to the metal beneath.
When first raised from the sea- water the plumbago becomes ex-
ceedingly hot from the action of the atmosphere. It may be cut
with a knife like an ordinary pencil.
When enough iron is melted (the common charge being two and
272 THE PRACTICAL METAL-WORKER1 S ASSISTANT.
a half to four cwt., but sometimes above twelve tons), the cupola is
tapped in front, at a hole close to the bottom, which allows the
whole contents to run out, either into ladles or, in very large works,
into channels leading directly to the moulds. The furnace is not
unfrequently tapped whilst the charge of metal is being melted,
and in such cases when the required quantity has been removed
into the ladles, the fireman re-stops the tap-hole by a conical plug
of clay on the end of a wooden bar. The process is called lotting,
and requires a dexterous hand, or the whole contents of the fur-
nace may escape.
In pouring iron, the means of conveying the melted metal to the
flasks differ with the quantity. One man will carry from fifty to
seventy pounds in a hand-ladle ; three to five men will carry from
two to four cwt. in a double hand-ladle, or a shank ; larger quan-
tities, amounting to sometimes from three to six tons, are carried
in the crane-ladle. These all possess one feature in common,
namely, their handles or pivots are placed but slightly above the
centre of gravity of the ladles, — they may therefore be tilted very
readily, as their fluid contents in obeying the law of gravitation
are almost neutral in the operation of tilting, which they scarcely
assist or retard, unless by mismanagement the ladle is over-filled,
and thus rendered top-heavy.
All these ladles are coated with a thin layer of loam, and every
time before use they are brushed over with black wash and care-
fully dried. The hand-ladle has a handle three or four feet long,
with a crutch or cross piece at the end, which is mostly held in
the left hand. Frequently the contents of half-a-dozen or more
hand-ladles are poured simultaneously into the same flask. The
shank has a single handle on the one side, and one made in two
branches at the other, and together they measure six to eight feet
in length. The tilting is completely under the command, of the
one or two men at the double handle.
The crane-ladle is carried from the furnace to the mould by the
swinging and traversing motions of the crane, which is similar to
those used at the iron forges, etc. (see p. 87), and in very large
foundries the plan of the building is divided into imaginary
squares, with a crane in the centre of every square, so that the
ladle is walked from one to the other, even to the far end of the
shop, with great facility and expedition.
The bail or handle of the crane-ladle is fixed in its perpendicular
position by the guard, a simple bolt, which prevents the ladle from
being overset by accident until it has reached its destination. Two
long handles, terminating in forked branches, are now fitted by
their square sockets upon the swivels or pivots of the crane-ladle,
and secured by transverse keys, — after which the guard is with-
drawn ; and then the two men at the ladle, two others at the crane,
and one to skim the dross from the lip of th,e ladle, commonly
suffice to manage two or three tons and upwards of fluid iron with
great ease and dexterity.
CASTING AND FOUNDING. 273
It has added to the pivot of the large cradle-ladle a tangent-screw
and worm'- wheel, by which it may be gradually tilted by one man
standing directly in front at any convenient distance ; and another
man skims the metal by a kind of throttle- valve coated with clay,
which sweeps into the lip of the ladle and keeps back the sullage :
the axis of the skimmer is continued as a long rod at right angles
to the first, and also terminating in a cross. By these arrange-
ments any precise quantity of metal can be delivered, and the risk
of accident scarcely exists.
The observations offered on p. 252 respecting the temperature
of the metal suitable to different brass works, might be here in a
great measure repeated — namely, that the smallest castings require
very hot metal, and a gradually lower temperature is more suita-
ble to works progressively heavier, to avoid their becoming sand-
burned or rough -on the face from the partial destruction of the
mould.
When cast-iron is very hot, the metal scintillates most beautifully,
far more vividly than a mass of wrought-iron raised above the weld-
ing heat; as the metal cools, the sparks become intermittent, and
at last the metal remains entirely quiet, excepting a multitude of
lines vibrating in all directions, as if the surface were covered with
thousands of wire-worms in great activity ; this effect lessens until
the metal^ solidifies. The softest iron shows most of this play of
lines, or is said to breo^k the best.
Iron castings are generally much heavier than those of brass,
and the melting heat of the metal being considerably higher, the
quantity of gas generated is very much greater ; additional care is
consequently required to provide for its escape, or the explosions
are much more violent. The sand is punctured at many places
with a fine wire, before the removal of the patterns ; sometimes also
more coarsely as soon as the metal has become solidified. The
gases issuing from the filled moulds are often lighted, either by the
red-hot skimmer, or by a torch of straw with which the moulds are
flogged : this lessens the accumulation of gas and the consequent
risk of accident.
The pouring of very large objects in open moulds, such as plates,
beams and girders, is a very beautiful and grand sight. The metal
is led from the furnace through a gutter lined with sand, into a
large trough or sow, the end of which is closed with a shuttle ; when
the sow is full, the shuttle is raised ; this allows the metal to flow
very quickly into the mould, but enables it to be kept back should
it be unnecessarily hot; the castings made in open moulds are
generally covered up with sand as soon as the metal is set.
The above, and the casting of smaller objects, such as flat plates
in open moulds, may appear amongst the most certain modes of
procuring sound castings ; but unless the air be well drawn from
the lower surfaces, they will become honeycombed or full of air
bubbles. This defect is avoided by making the sand-bed sufficiently
18
274 THE PRACTICAL METAL-WORKER'S ASSISTANT.
porous, and pricking it with many holes just below the surface, to
serve as horizontal aj'r-drains.
A far greater number of works are cast in close moulds, and in
the horizontal position ; the proportionate quantity of metal is car-
ried to them in ladles ; skimmers are held to the lips of the moulds
at the time of pouring, to keep back all the sullage or dross. The
number, position, and height of the runners, are determined by cir-
cumstances ; generally not less than two apertures are provided,
the first for the entry of the metal, the second for the escape of
the air, and to allow the metal to flow through the mould and carry
off the sullage.
Sometimes in heavy castings, in addition to the runners one or
more large heads or feeds are made at the upper part, to supply
fluid iron as the metal shrinks in the act of solidifying ; and in some
such cases the feed is pumped, by moving an iron rod up and down
in the feed to keep the metal in motion, so that for a time the metal
may freely* enter and the air escape, to increase the general sound-
ness of the mass. The pumping should, however, be discontinued
the moment the metal begins to stiffen and clog the iron rod, or in
other words to crystallize, otherwise mischief instead of benefit will
accrue.
Works which are required to be particularly sound, as some
cylinders, pipes, shafts and plungers, are cast vertically ; the moulds
are sunk in the earth, and well rammed to enable them to with-
stand the great pressure of the fluid column, without becoming
strained or bursting open. Such objects are moulded and poured
with a head, or an additional portion about one-third the length
of the finished casting, as mentioned in respect to brass guns.
In pouring cylinders of tolerably large size, the metal is conducted
from the sow through two sunk passages with side branches, en-
tering the mould in the direction of tangents about one-third from
the bottom ; these keep the metal in circulation, and assist the rise
of the sullage ; cylinders are also poured through holes in the loam
cake, other apertures being always provided in it for the escape of
the air. Beneath the iron plate upon which the mould is built, is
placed a central mass of hay-bands, in order that the air may have
free passage to collect, and then to escape upwards to the surface
of the earth, through one, two, three, or more internal or external
tubes, as the case may be. The thick cylinders for hydrostatic
presses are closed at one end, and those cast with the mouth down-
wards, require an air tube bent at each end, to lead from the core
beneath the casting to the surface of the earth ; the gas drives out
in a stream, and is immediately ignited like a great torch : others
prefer casting them with the mouth upwards, in order that less risk
may exist of locking up air within the casting.
For the very heaviest works the three or four furnaces are
usually tapped at the same moment, the stream! from every one is
conducted through a sand trough, and they all unite in one great
trunk leading to the mould.
CASTING AND FOUNDING.
275
In pouring some of the largest cylinders, the trough is led en-
tirely round the top of the loam mould, and from the circular
channel, sometimes as many as thirty runners, every one of which
is stopped by a shovel held by a man or a boy, descend to the
mould, and as many air holes are made between the ingates. When
the foreman sees that all the furnaces are in full run, and that the
channels are well supplied, he gives the word, "up shovels ;" they
rise at the instant, and allow' the molten stream to deposit itself in
its temporary resting-place.
At the time the cylinder is poured, all the precautions explained,
p. 266, are necessary to give the mould sufficient strength to resist
the pressure of the fluid metal ; but as soon as it becomes set, the
conditions are altered, and this resistance must be removed from
the inner surface, that the cylinder may shrink in cooling without
restraint or fracture. Accordingly, after three or four hours' time,
all the diametrical iron stays are knocked away by a vertical weight
or monkey, and men descend by iron ladders into the cylinder, to
break down the brick core. The heat is so terrific, that they can
only endure it for a minute or so at a time, but still the precaution
is imperative : and even in comparatively small castings of hollow
objects, such as cylinders, pans, and boxes, it is desirable to break
down the cores, to prevent the castings from scoring or breaking.
Although some iron castings employed for bridges, girders, and
even for machinery, require the enormous quantities of iron re-
ferred to, on the other hand this useful metal is employed for
exceedingly light and beautiful castings, abundant examples of
which may be seen in the Berlin ornaments and chains. The
links of most of the Berlin chains are connected with wrought-
iron wire, but Figs. 173 and 174 represent a chain made entirely
by the process of casting.
Figs. 173
174.
Its
length is 4 feet
10 inches. It consists of about 180 links.
and weighs If oz. avoirdupois. It was thus made : The larger
links a a were first cast separately ; a solid model of the chain
about 8 inches long, with core prints, as in Fig. 174, was then
moulded. The links a, previously smoked to prevent the adhesion
of the metal, were first laid in the mould, and afterwards the sand
cores b b, and a separate runner was made to every one of the
small links c c, so as to unite the whole when poured.
The concluding duty of the iron-founder is to remove the cast
276 THE PRACTICAL METAL-WORKER'S ASSISTANT.
ings from the mould and to break off the runners. After this all
the loose sand (which is reserved for making the partings of future
moulds) is scraped off with iron shovels and wire scratch brushes,
and the seams are smoothed off with chisels and old files.
The skin or crust of a casting made in a sand mould is in
general harder than that of a loam casting. This appears to occur
from the former being partially chilled by the moisture of the sand.
In some cases, as in the teeth of wheels, it is desirable to retain
this hard sand coat on account of its greater durability ; but when
the crust is partially removed from thin or slight works, it con-
stantly happens that they spring or become distorted whilst under
the treatment of tools, from the general balance of strength being
disturbed by the partial removal of the crust. This gives rise to
continual interferences, which come however under the considera-
tion of the mechanician rather than of the founder.
The crust of the casting, which always retains some sand, is
very destructive to the tools, unless they can be sent in deep
enough to penetrate to the clean metal beneath. When but little
is to be removed from the casting, or that they are wrought with
expensive tools and circular cutters, it is desirable to pickle the
works, or to undermine the sand by dissolving a little of the metal
with some acid.
Iron castings are pickled with sulphuric acid diluted with about
twice as much water. The castings, if small, are immersed in a
trough lined with lead ; or else the acid is sprinkled over them.
In two or three days a thin crust, like an efflorescence, may be
washed off with the aid of water and slight friction.
Brass and gun-metal, when pickled, require nitric acid diluted
with four to six times as much water, otherwise the rough coat
should be removed with an old file or a triangular scraper, but
which is less effective than the dilute acid. This acid liquor should
be also kept in leaden vessels, or in those of well -glazed earthen-
ware or glass. The yellow brass is much improved by a good but
equal condensation with the hammer, and in fact to whatever action
the metals are subjected, whether natural in the mould, or artificial
under the hammer and tools, it is of primary importance that all
parts should be treated as nearly alike as possible.
NEW METHOD OF MANUFACTURINGS DROP SHOT. — David Smith,
of the house of Le Roy and Co., 263 Water Street, New York,
has invented and put into practice a new mode of manufacturing
drop shot. The chief feature of this invention consists in causing
the fused metal to fall through an ascending current of air, which
shall travel at such a velocity that the dropping metal shall come
in contact with more particles of air, in a short tower, than it
would in falling through the highest towers before in use.
Fig. 175 is a vertical sectional elevation of a sheet metal cylinder,
set up as a tower within a building, and may be about 20 inches
internal diameter, and 50 feet high or less. This tower, although
mentioned in Smith's patent, is now dispensed with in the middle
CASTING AND FOUNDING.
277
of the heiglit; so that only an open space remains. Fig. 176 is a
Fig. 175.
x A z
plan at the line a b ; Fig. 177 is a plan at the line qr; Fig. 178 ia
a section at op ; and Fig. 179 is a section at m n, Fig. 175
Fig. 178.
Fig. 179
^ C is a water -cistern beneath the tower. B is a pipe from the
Vowing apparatus leading into the annular chamber /; the upper
surface g is perforated as shown in Fig. 177, to dispense the ascend-
278 THE PRACTICAL METAL- WORKER'S ASSISTANT.
ing air. The outer side of this annular ring f forms the base of a
frustum of a cone, forming the tower D, passing the blast through
the frame y y, Fig. 178 ; and in Fig. 175 is shown to support a
cylindrical standard K, the upper central portion of which receives
the pouring pan A. This pan is charged with each separate size
of shot. Round the pouring pan A is a circular waste trough z.
The object of this arrangement is that the fluid metal running
through the pouring pan A into the ascending current of air, will
be operated upon in the same manner as if it fell through stagnant
air of great height The shot falls through the open centre of the
ring f into the water cistern C, where a shoot t carries it into the
tub S, which when full may be removed through x, an aperture in
the cover of the cistern.
CHAPTER XVI.
WORKS IN SHEET METAL, MADE BY JOINING.
ON MALLEABILITY, ETC. ; DIVISION OF THE SUBJECT. — The
process of casting, which has been recently considered under so
great a variety of forms, is one of the most valuable courses of
preparation to which the metallic materials are submitted. In the
foundry, the metals are made to assume an infinitude of the most
arbitrary shapes, but which are in general more or less thick or
massive. It is now proposed to consider a few of the methods and
principles of a very extensive and serviceable employment of the
malleable metals and alloys, which (excepting iron) are cast into
thick slabs or plates, and then laminated into thin sheets between
cylindrical rollers.
Rollers have been used for a considerable period in the manu-
facture of sheets of malleable iron, steel, and copper, when in the
red-hot state, but most others of the metals and alloys are rolled
whilst cold ; and which economic application of power often nearly
supersedes the use of the hammer, as it performs its function in a
more uniform and gradual manner, and at the same time increases
to the utmost the hardness, tenacity, elasticity and ductility of
such of the metals and alloys as are submitted to this and similar
courses of preparation for the arts. These processes of condensa-
tion cannot be carried to the extreme without frequent recurrence
at proper intervals to the process of annealing ; and in rolling the
thinnest sheets of metal, several are frequently sent through the
rollers at the same time ; but, as in the instances of tin-foil, gold
and silver leaf, and some others, the hammer ig -again resorted to
after the metals have been rolled as thin as they will economically
admit of, in this process of part-manufacture.
WORKS IX SHEET METAL. 279
None of these preparations of the metals can go on without a
material internal change of their substance, to which the celebrated
Dr. Dalton thus refers : *' Notwithstanding the hardness of solid
bodies, or the difficulty of moving the particles one amongst the
other, there are several that admit of such motion without fracture,
by the application of proper force, especially if assisted by heat.
The ductility and malleability of the metals need only be men-
tioned. It should seem the particles glide along each other's sur-
face, somewhat like a piece of polished iron at the end of a magnet,
without being at all weakened in their cohesion."
This gliding amongst the particles of metals is exemplified by
the action of thinning them by blows of the hammer ; likewise by
the actions of laminating rollers and the draw-bench, in which
cases the external layers of the metals are retarded or kept back
as it were in a wave, whilst the central stream or substance con-
tinues its course at a somewhat quicker rate. The necessity for
annealing occurs when the compression and sliding have arrived
at the limit of cohesion. Beyond this the parts would tear asun-
der, and produce such of the internal cracks and seams, met with
in sheet-metal and wire, as are not due to original flaws and air-
bubbles, which have become proportionally elongated in the course
of the manufacture of these materials.
A sliding or gliding of a very similar nature occurs also in
every case in which the metals are bent ; and this differs only in
degree, whether we consider it in reference to a massive beam, a
permanently flexible spring, a piece of thin sheet-metal, or a film
of gold leaf. For instance, the curvature of a cast-iron beam,
originally straight, is produced by the stretching or extension of
the lower edge, and the shortening or compression of the uppei
edge, the central line remaining unaltered during the process, ex-
cept it is bent. In like manner a spring derives its elasticity from
the extension and compression of its opposite surfaces at every
flexure ; and the spring remains permanent, or endures its work
without alteration of form, when the bending is not carried beyond
its limit of elasticity ; but when it is bent beyond a certain point,
the spring either retains a permanent set or distortion, or it will
break. In the same manner the beam, when only bent to the limit
of its elasticity, returns to its original form when the load is re-
lieved, and the constant study of the engineer is so to proportion
the beam that it may never be required to exceed nor even to
arrive at the limit of its elastic force. For those parts of mechan-
ism exposed to sudden shocks and strains, he will employ
wrought-iron, the cohesive strength of which is considerably
greater than that of cast-iron, although less than that of steel,
which is the strongest and most permanently elastic of all metallic
substances.
The thin metals also possess some elasticity, but this dies away
before they reach the tenuity of leaf gold, in which, however, the
bending cannot be accomplished without a similar change in the
280 THE PRACTICAL METAL-TVORKER's ASSISTANT.
arrangement of its opposite sides, although the difference is be
yond the reach of our physical senses.
If we desire to wrap a piece of gold leaf around a cylinder of
half an inch diameter, so small is the resistance that the least puff*
of breath suffices. A piece of thin tin-foil offers no more resist-
ance than writing-paper. Thin latten-brass, or China tea-lead, is
bent more easily than a card ; brass and iron the thirtieth or forti-
eth of an inch thick, could be readily bent with a wooden-mallet ;
but metal of one-eighth of an inch thick would call for smart blows
of a hammer, and in iron and steel the further assistance of heat
would be likewise required, because in the last case a very con-
siderable amount of the sliding motion of the metal would be called
into play. .
For example, the piece of metal J of an inch thick, was originally
flat and of the same size on its opposite surfaces ; whereas now,
neglecting any alteration of thickness, the inner part would equal
the circumference of a circle J an inch diameter, and the outer that
of a circle of f inch diameter; or it would become 1J and 2J
inches long respectively on its opposite surfaces. To produce this
change of dimensions would necessarily require far greater force
than the bending of the gold leaf, the internal and external meas-
ures of which, viewed as a cylinder, could be ascertained alone by
calculation, and not by ordinary means. On the other hand, the
sliding of the thick sheet of metal would be illustrated most dis-
tinctly, if several pieces of writing-paper, equal to the original
metal individually in surface and collectively in thickness, were
wrapped around the same cylinder. The inner paper would ex-
actly meet, the outer would present an open seam } inch wide.
The metals possessed of the malleable property undergo a nearly
equal change in their arrangement ; but the unmalleable or brittle
metals break.
Several of the processes of working the sheet metals are closely
analogous to those employed in forging ordinary works in iron and
steel, — the difference being mainly such as arise from the tliin and
thick states of the respective materials, and their relative degrees
of rigidity or resistance. The illustrations will be selected indis-
criminately from various trades in which the sheet metals are em-
ployed. It appears desirable, however, to separate the subject into
two principal parts, namely, the formation of objects some lines of
which are straight, and the formation of objects no lines of which
are straight.
The first division comprehends all objects with plane, cylindri-
cal or conical surfaces, such as may be produced in pasteboard by
cutting out the respective sides, either separately or in clusters, and
combining them in part by bending, and in part by cement. Simi-
lar works in metal are often produced by the precisely analogous
means of cutting, bending, and uniting, and which call for increase
of strength in the methods proportioned to the rigidity of the
materials.
WOuKS IX SHEET METAL. 281
The second division comprehends all objects with surfaces of
•iouble curvature, including spherical, elliptical, parabolical, and
arbitrary surfaces, as in reflectors, vases, and a thousand other
ihings, none of which forms can be produced in stiff pasteboard,
because this material is incapable of being extended or contracted
m different parts in the manner of sheet metal. This is easily
shown, by the following case, amongst others.
Terrestrial globes are covered with thin paper, upon which the
delineation of the surface of the earth has been printed : the paper
may be cut into twelve gores, or fish-shaped pieces, all including
thirty degrees from pole to pole. A globe is usually covered with
26 pieces of paper, namely, 2 pole papers, or circles including 30°
around each pole; and 24 gores meeting at the equator. Sometimes
the gores extend from the pole to the equator ; every gore has then
a narrow curved central notch extending 30° from the equator.
But the same gores cut out of pasteboard could not be applied to
the surface of a globe, as pasteboard does not admit of that degree
of gradual extension and contraction, required for the production
of spherical and similar raised forms, from pieces originally flat, but
will become abruptly bent and torn in the attempt.
On the contrary, a round disk of metal may be beaten into a
hemisphere, or nearly into a sphere ; but even thin paper is only
possessed of this quality in a very limited dogree, for the globe
could not be smoothly covered with so few as two, three, or four
pieces of the thinnest paper without its puckering up, showing that
some parts of the material are in excess. The gliding property, or
that of malleability and ductility, possessed by the metals, is indis-
pensable to adapt the flat plate to the sphere, by stretching the
central portion and gathering up the marginal part, an action that
admits of some comparison to the extension or compression of the
slides of a telescope, except that the metal becomes thicker or
thinner instead of being duplicated on itself.
WORKS IN SHEET METAL, MADE " BY CUTTING, BENDING, AND
JOINING. — Every one in early life has made the first step towards
the acquirement of the various arts of working in sheet metal, in
the simple process of making a box or tray of card ; namely, by
doubling up the four margins in succession to an equal width,
then cutting out the small squares from the angles, and uniting the
four sides of the box, either edge to edge, by paste, sealing-wax, or
thread, or in similar manners by lapped or folded joints. A dif-
ferent mode is to make the sides of the box as a long strip, folded
at all the angles but one; or lastly, the bottom and sides may be
cut out entirely detached, and united in various ways.
In the above, and also in the most complicated vessels and solids,
it is necessary to depict on the material the exact shape of every
plane superficies of the work, as in the plans and elevations of the
architect ; and these may be arranged in any clusters which admit
of being folded together, so as to constitute part of the joints by
bending the material. Thus, a hexagonal box, Fig. 180, can be
282
THE PRACTICAL METAL-WORKERS ASSISTANT.
made by drawing first the hexagon required for the bottom, as in
Fig. 181, and erecting upon every side of the same a parallelogram
equal to one of the sides, which in this case are all exactly alike ;
otherwise the group of sides can be drawn in a line, as in Fig. 182,
and bent upon the joints to the required angle, or 120 degrees.
Either mode would be less troublesome than cutting out seven
detached pieces and uniting them ; the addition of one more hexa-
gon, dotted in Fig. 182, would serve to complete the top of the
hexagonal prism, by adding a cover or top surface.
The same mode will apply to polygonal figures of all kinds,
regular or irregular; thus Fig. 183 would be produced when the
group of sides in 184 were bent around the irregular octagonal
base ; or that the sides of 185 were separately turned up
Figs. 180
181
182
183
185.
The cylinder is sometimes compared with a prism of so many
sides, that they melt into each other and become a continuous
curve ; and if the hexagon in Fig. 182 were replaced by a circle,
and the group of sides were cut out of equal length with the cir-
cumference of that circle, and in width equal to the height of the
vessel, any required cylinder could be produced. And in like
manner any vessel of elliptical or similar forms, or those with par-
allel sides and curved ends, and all such combinations, could be
made in the manner of Fig. 184 (provided the sides were perpen-
dicular), by cutting out a band equal in length to the collective
margin of the figure, as measured by passing a string around it ;
or the sides might be made of two, or several pieces, if more con-
venient, or if requisite from their magnitude.
All prismatic vessels require parallelograms '-to be erected on
their respective bases ; but pyramids require triangles, and frustums
of pyramids require trapezoids, as will be explained by Figs. 137
WORKS IX SHEET METAL.
283
and 188, which are the forms in which a single piece of metal
must be cut, if required to produce Fig. 186. Every one of the
group of sides, must be individually equal to one of the sides of the
pyramid, whether it be regular or irregular, and 186 being an erect
and equilateral figure, all the sides in 187 and 188 are required to be
alike, and would be drawn from one templet: an irregular pyramid
would require all its superficies to be drawn to their absolute forms
and sizes.
Figs. 186
187
188
189.
The cone is sometimes compared with a pyramid with exceed-
ingly numerous sides (as the cylinder is compared with the prism),
and Fig. 189, intended to make a funnel or the frustum of a cone
of the same proportions as 186, illustrates this case. The sides of
the cone are extended until they meet in the centre o, Fig. 186, and
then with the slant distances o a, and o b, the two arcs a a, and b b,
are drawn with the compasses, from the centre o ; and so much of
the arc a a, is required as equals the circumference a, of the cone :
the margins a b, a b, are drawn as two radii. When the figure is
curled up until the radial sides meet, it will exactly equal the cone,
and the similitude between Figs. 188 and 189 is most explanatory,
as 189 is just equal to the collective group of the sides required to
form the pyramid.
It will now be easily seen that mixed polygonal figures, such as
Figs. 190, 192, and 19-i, may be produced in a similar manner,
provided their sides are radiated from the square, the hexagonal
or other bases, in the manner of Figs. 191, 193, 195, but the sides
of the rays not being straight, it is no longer possible to group
them by their edges, as in Figs. 182, 184, and 188. The object
with plane surfaces, Fig. 190, is only the meeting of two pyramids,
at the ends of a prism, and when unfolded, as in Fig. 191, the centre
a, is' equal to the base a, of the object ; the sides b, radiate and ex.-
284
THE PRACTICAL METAL-WORKER' S AS3ISTAXT.
pand from the hexagon at the angle of the faces of the inverted or
lower pyramid b, and their vertical height in the sheet is equal to
the slant height in the vessel ; the superficies c, are those of a prism,
therefore they continue parallel, and have the vertical height of the
part c, of the figure ; lastly, the sides d, again contract as in the
original, and at the same angle as the sides of the six upper faces ;
in a word, the faces b, c, d, are identical in the vase and in the radi-
ated scheme.
Figs. 190
195.
Should the vessels, instead of planes, have surfaces of single cur-
vature, as in Figs. 192 and 194, the method is nearly as simple.
The object is drawn on paper, and around its margin are marked
several distances, either equal or unequal, and horizontal lines or
ordinates are drawn from all to the central line. The radiating
pieces for constructing the polygonal vases are represented in Figs.
193 and 195, in which the dotted lines are parallel with the sides
of the hexagons or the bases, and at a distance equal to those of
the steps 1, 2, 3, to 8, around the curve of the intended vases ; the
lengths of these lines, or ordinates, 1 1, 2 2, 3 3, are in regular
hexagonal vessels exactly the same in the radiated plans as in the
respective elevations, because the side of the hexagon and the radius
of its circumscribing circle are alike.
In all other regular polygonal vessels the new ordinates will be
reduced for figures of 8, 10, and 12 sides, in the same proportions
as the sides of these respective polygons bear to the radii of their
circumscribing circles, and the ordinates for 3, 4, and 5 sided
figures will be similarly increased.
All the above cases could be accurately provided for without
any calculation, by the employment of a very simple scale repre-
WORKS IN SHEET METAL.
285
sented in Fig. 196, in which the angle 3 of, shall contain 120 de-
grees, or the third of a circle ; 4 o f, 90 degrees, or the fourth ;
5 of, 72, or the fifth ; 6 of, 60, or the sixth; and 8, 10, and 12, re-
spectively the 8th, 10th, and 12th parts of a circle. The circular
arcs are struck from the centre o, and may be the 6th, 8th, 10th of
an inch, or any small distance apart.
To learn the altered value of any ordinate, as for constructing a
vase like the several figures 190, 192, 194, but with 10 sides ; we
will suppose the original ordinate to reach from o to x on the
radius of, the required measure would be the length of the arc
x x , where intersected by the line 10, or that for a decagon ; but
it would be more convenient to make the angle half the size, as
then the new ordinate would be at once bisected, ready for being
set off on each side the central line of the radiated plan. When
one side had been carefully formed, a curved templet or gage
would be made to the shape, by which all the other sides could be
drawn. .
For polygonal vessels with unequal sides, such as Fig. 197, the
curvatures of the edges of the rays will be identical, notwithstand-
ing the difference of the sides. For example, the octagon drawn
in the one corner shows that the figure resembles the regular octa-
gon as far as the angles are considered ; and that the regular
octagon may be considered to be cut into four quarters and to be
removed to the four corners, by the insertion of the two pairs of
intermediate pieces a a, and b b, which latter would necessarily be
parallel. In the like manner a pyramidal vessel built upon the
same base, would require equal angles for all its sides.
It would have been easy to have extended these particulars to
numerous other figures, such as the regular geometrical solids,
oblique solids, and many others, but enough has been advanced to
explain the cases of ordinary occurrence, and in the delineations
of which, the tinman, coppersmith, and others are very expert.
197.
/
Much of that which has been stated, as it will eventually appear,
has been partly advanced in elucidation, on the less apparent
methods practised in making similar forms out of flat plates, by
the process called raising ; this is done with the hammer alone, by
stretching some parts of the metal and contracting others (the
286
THE PRACTICAL METAL-WORKERS ASSISTANT.
drawing and upsetting of the blacksmith), a process not required in
any of the foregoing figures, the whole of which might be made in
pasteboard, a material that, as before observed, does not admit of
being raised or bulged into figures of double curvature.
The various works having been drawn upon the sheet of metal,
the first process is to cut them out ; this is almost always done
with the shears ; sometimes, however, for thick metal, the cold-
chisel and hammer are used, the work being laid upon the bare
anvil or upon a cutting-plate, as in forging ; occasionally the metal
is fixed in the jaws of the tail-vice, and cut off with the cold-chisel
applied in contact with the vice ; the edge of the chisel is placed
nearly parallel with the jaws, which serve as a guide. In some
cases very long vices, with a screw at each end, are used in a simi-
lar manner, for the thick iron plates employed for boilers ; but the
shears are the most generally convenient.
Although the tools used in working the sheet-metals are ex-
tremely various as regards their sizes and specific forms, they may,
with the exception of the shears and soldering-tools, be principally
resolved into numerous varieties of hammers, anvils, swage-tools,
and punches. Figs. 198 to 212 represent some few of the most
common of these tools, which are used alike both in bent and
204.
208 209 210 211
raised works, and their close resemblance to those for ordinary
forging in iron and steel will not escape observation. The most
remarkable points of difference are in their greater height and
length, which enable them to be applied to the interior of large
WORKS IX SHEET METAL. 287
objects, and also in their square shanks, by which they are fixed
in holes in the wooden blocks and benches.
The hammers are nearly alike at both ends ; many of them
have circular faces, either flat or convex ; others resemble the
straight or cross-panes of ordinary hammers, and are also eithei
flat or convex ; and those used in finishing, are exceedingly bright,
in order that they may impart their own degree of polish to the
•work, which process is called planishing.
When thin metal is struck between tools both of which are of
metal, it is invariably more or less thinned ; and should the blows
be given partially, such parts will become stretched or cockled, and
will distort the general figure. It is therefore usual, whenever
admissible, to employ wooden hammers of the forms described,
and also wooden blocks or anvils when metal hammers are used ;
reserving the employment of tools both of metal, either for the con-
cluding steps, or for those cases, where from the substance of the
metal and the nature of the work, the wooden hammers would be
ineffective, or a greater definition of form is required than wooden
tools could give.
The anvil used by the coppersmith and similar workmen is
usually square, say from six to eight inches on every side ; and the
smaller anvils, which are called stakes, and also teests, are of pro-
gressively smaller sizes, down to half an inch square, and even
less. Some of them have one edge rounded like 201 ; others have
rounded' faces as 202 and 203 ; a few assume the form of a rounded
ridge, like Fig. 205 ; and many have bulbs or buttons, as if turned
in the lathe, as in Fig. 206.
The beak-irons are also very unlike those used by the smith ;
they are seldom attached to the anvil, and are often exceedingly
long, as in Fig. 199 : some few, for more accurate purposes, are
turned in the lathe to the conical form, like 204 ; these are held in
the vice, the jaws of which enter grooves in the shank ; and man-
drels four to six feet long, used for making long pipes, are attached
to the bench by long rectangular shanks and staples.
Fig. 198, the hatchet-stake, is from two to ten inches wide ; it is
very much used for bending the thin metals, in the same manner
as the rectangular edge of the anvil is used for those which are
thicker ; a cold-chisel fixed in the vice forms a small hatchet-stake ;
207 is the creasing-tool for making small beads and tubes ; 208 is
the seam-set for closing the seams prepared on the hatchet-stake ;
209 is a hollow and 210 a solid punch; the cutting edge of the
former meets at about the angle, of fifty degrees, the latter is solid
at the end for small holes; both are struck upon a thin plate of
lead or solder laid upon the stake; 211 is a riveting-set or punch
for the heads of rivets ; and 212 is the swage-tool, a miniature of
the tilt-hammer, to which a great variety of top and bottom tools,
or crease*, are added, which greatly economize the labor of making
different mouldings and bosses ; the stop is used to retain the par-
allelism of the mouldings with the edge of the metal, and a similar
stop is also at times applied to the hatchet-stake, 198.
288
THE PRACTICAL METAL-WORKER'S ASSISTANT.
The sides of the vessels represented in Figs. 180 to 195, if the
metal were thin, would be bent to the required angles by laying
the metal horizontally upon the hatchet-stake, with the lines ex-
actly over the edge of the same, and blows would be given with
the mallet, (or with the hammer for more accurate angles), so as to
indent the metal with the edge of the stake ; it would be then bent
down with the fingers, unless the edge were very narrow as for a
seam, when the mallet would be alone used. Thicker metal is
more commonly bent over the square edge of the anvil, as in Fig.
59, p. 104, a square set or hammer being held upon its upper sur-
face; and sometimes the work is pinched fast in the vice, and it is
bent over with the blows of a flat-ended punch or set, applied
close in the angles, and then hammered down square with the
hammer ; very strong metal is seldom bent in this manner, but the
sides of objects are then made separately, and united in some of
the ways which will be explained.
In bending thin metals either to circular or other curves, they
are held on the one edge in the hand, and curled on the opposite
edge over beak-irons or triblets with the mallet ; when the metal
is too stubborn or too narrow to be thus held in the hand (as the
copper-smith scarcely ever uses tongs, except at the fire), the metal
is driven into a concave tool to curl up the edges. For instance,
the crease, Fig. 207, is frequently employed for making small
tubes or edging; the strip of metal is laid over the appropriate
groove, and an iron wire is driven down upon it with the mallet ;
this bends it like a wagon-tilt ; the edges are then folded down
upon the wire with the mallet, and it is finished by a top tool, or
a punch, Fig. 208, having a groove of similar concavity or radius
to that in the crease.
For half-round strips, the crease together with the round wire
suffice, or they would be more quickly made in the swage-tool,
212, and which might in this manner be made to produce any par-
ticular section or moulding, and that at any distance from the edge
by means of the stop or gage. Large tubes are always finished
upOn beak-irons, such as Fig. 199, the round ends of which serve
for curvilinear, and the square ends for rectilinear works.
Figs. 213
a c'
All the sheet metals up to the thickest boiler plate are treated
much after the same general methods ; large cast-iron moulds of
WORKS IX SHEET METAL.
289
various sweeps are employed, the stout iron being heated to red-
ness, and set into them with set hammers struck with the sledge.
"When a circular bend is wanted in the centre of a long piece, it
is conveniently and accurately done by bending it over a ridge,
such as a parallel plate with a rounded edge, or a triblet, the ends
of the work serving for a purchase, or as levers. . Thus Fig! 213
shows the common mode of bending thick plates to the form of
the piece, a b, c', for the internal flues of marine boilers; the plate;
is heated to redness in the middle, and pressed down until a c
assume the posit' ons a c'.
In a similar manner, to bend long strips into easy curves, such
as for cylindrical vessels, the tinmen use & former, Fig. 214, a cylin-
drical pieca of wood from two to four inches in diameter, and two
feet long,. turned with a pivot at the one end; the pivot is laid
upon the edge of the bench, and the man rests his chest against
the other extremity of Fig. 214, to support it in the horizontal
position. The tin plate is first stretched in the hands by the two
corners, a, c, and rubbed over the former diagonally, to bend it at
every part ; this is repeated across the other diagonal to flatten the
plate ; it is afterwards folded round the stick, and rubbed forcibly
down with the hand, as at d, to give it an easy bend approaching
to the required curvature. Should the vessel require a bed at the
upper edge, it is usually made by the swage tool, Fig. 212, before
the plate is curled up; the work is then much more rigid, and
requires additional force to bend it.
Fig. 215 is intended to explain a very simple and useful machine,
first employed by the tinmen for rolling up the cylinders for spring
window-blinds, the sides of culinary vessels and similar works, and
now also by the boiler- makers, and' others for the strongest plates
It has two cylindrical rollers, a, b, and d, which are connected by
toothed wheels so as to travel in opposite directions, thus far ex-
actly the same as a pair of laminating rollers for making the sheet
metals; the third roller c, is just opposite the two, and is free to
-move on its pivots, as it is unconnected with a, b, and d] and the
third roller c, is capable of vertical adjustment.
19
290 THE PRACTICAL METAL-WORKERS ASSISTANT.
When, therefore, the metal is moved along by the carrying
rollers a b, and d, it strikes against the edge of the bending roller c,
and is curled up to enable it to pass over the same ; and as this
bending occurs in an equal degree at every point of the sheec of
metal, it assumes a circular sweep, the radius of which is depen-
dent on the place of c. In the central position, the sheet would
assume the circle e,ffg" and when c is more raised as to the upper
position, the metal would follow the dotted circle, the radius of
which is much less ; and when the bending roller c, is placed out
of level, the works are thrown into the conical form.
Fig. 216 shows the application of the bending rollers to boiler
plates ; none of the rollers a, b, c, touch each other, and b is under
adjustment for different curvatures.
In the last four figures the same principle is employed, namely,
the application of three forces as in a lever of the first order, or as
in bending or breaking a stick across the knee. The school-boy's
problem of "drawing a circle through three given points" is
thoroughly exemplified in Fig. 216 and in 215, the one force is the
grip of the plate on the line of centres of a, b, d ; the roller c, curls
the plate partly around the roller a, and the point at which the
plate leaves a b, may be called the second force, or b ; the third is
the point of contact on c.
One of the most useful applications of the bending machines, is
in straightening the metals, which may at first appear to be a mis-
application of words, but in truth by the depression of c, to about
the position of c', it only bends the plate for the moment, just to the
limit of its elasticity. It results that when it has been passed
through twice, or with each side alternately upwards, the elastic
reaction just suffices to convert the figure temporarily given, or
that of the arc of an enormous circle, into a plane or true surface ;
and as this is done without- any blows, which produce partial con
densation at such spots, the plate is less subject to after changes
than if it had been hammered flat ; as by the rollers, every part of
the plate is bent exactly to the limit of its permanent elasticity. In
the tinmen's bending rollers, d, c, Fig. 215, are often turned with
half round grooves, to receive the thickened edge which contains
the wire employed to stiffen the tops of the vessels; sometimes
also the rollers are used for preparing the seam to contain the
wire. Grooved-rollers (similar to those shown on page 81) are
very extensively employed, likewise, in other works in the arts be-
sides the manufacture of iron, to which they are there more imme-
diately referred.
The use of the plain cylindrical roller at h, page 81, is so simple
as to be immediately apparent ; rollers with curvilinear edges, such
as at t, have been long employed for bending the steel and brass
plates for fenders ; similar rollers on a smaller scale and of numer-
ous patterns, many of them chased and ornam'ented, are used in
making jewelry, as for producing mouldings, headings, and matted,
checkered or other works
WORKS IN" SHEET METAL.
291
IMPROVED MACHINE FOR EOLLING UP SHEET METAL PIPE. —
This? MacHne is the invention of Mr. William Ostrander, of New
York, and is patented by Ostrander and Webster. It consists of
three rollers, L M B (the same as ordinary stovepipe rollers) ; J is
an independent pinion which mashes in the smaller ones fastened
to the rollers, L and M, which gives them both the same line of
motion ; the roller, B, is raised or lowered by the treadle, G, in
connection with F F, upon which rest the boxes of B. D D arc
set screws to adjust the height and pressure of B; I is a set scrtry,
Fig. 217,
which raises or lowers M, which regulates the space between L, M,
and B. K is a mandril constructed of wood, upon which the pipe
is formed ; it is covered with the same material that is desired to
be rolled or formed up by the machine, the seam or joint left un-
soldered, in which the sheet C is placed, and there held while being
formed between the three rollers. E is the pulley and belt; A
is the bench; H is the weight which is used only when the machine
is worked by a crank. The operation by steam is as follows : the
292
THE PRACTICAL METAL-WORKER 3 ASSISTANT.
rollers, L and M, are in constant motion, the mandril, K, is taken
out from the three rollers, and the edge of the sheet, 0, ft> be
formed, is slipped between the mandril and its covering ; it is then
laid in the space it occupies as represented in the engraving ; the
foot is applied to G, which raises the roller, B, until the mandril,
K, is brought in contact with L and M ; the three rollers, together
with the mandril, are revolved, and the sheet C, is drawn in and
formed closely about the mandril ; the foot is then removed from
G, which allows the roller, B, to drop down, and permits the man-
dril, K, to be taken out and the newly-formed pipe to be slipped
off, whose edge, in nearly every instance, will be "laid" close
enough for soldering : should the metal be so stiff and hard as to
prevent its edge being laid in the first rolling, it will be perfectly
so when rolled a second time on the bare wooden mandril. This
roller is capable of forming from three to five thousand feet of pipe
per 10 hours, in 20 inch joints, by a boy. It does not require the
use of mallets to lay the edges. It can be made as long as any
sheet of metal requires, inasmuch as the rollers can be braced from
the outside without being interfered with. It can be used in the
old way for stovepipe, etc., by removing the pinion, J, up out of
the way, and bringing the rollers, L M, close together.
This machine is now in practical use by Woolcock and Ostran-
der, No. 57 Ann Street, N. Y., who make large quantities of speak-
ing and other pipes with it.
ANGLE AND SURFACE JOINTS. — The next steps to be considered,
appear to be the methods of uniting the edges of the vessels after
they have been cut and bent to meet in angles, curves, or plane
surfaces. The principal modes of accomplishing this are repre-
sented in Figs. 218 to 240, which are grouped together for the
convenience of comparison.
Figs. 218 and 219 are for the thinnest metals, such as tin, which
require a film of soft-solder on one or other side. Sheet- lead is
similarly joined, and both are usually soldered from within.
Figs. 218 219 220 221 222 223 224 225 226 227 228 229.
Figs. 220 and 221 are the mitre and butt-jomts used for thicker
jnetals with hard solders. Sometimes 221 is dovetailed together,
the edges being filled to correspond coarsely ; they are also partly
riveted before being soldered from within. These joints are very
weak when united with soft solder.
Fig. 222 is the Zap-joint ; the metal is creased over the hatchet
WORKS IN SHEET METAL. 293
stake. Tin-plate requires an external layer of solder; spelter
solder runs through the crevice, and need not project.
Fig. 223 is folded by means of the hatchet-stake, the two are
then hammered together, but require a film of solder to prevent
them from sliding asunder.
Fig. 224 is the folded angle-joint, used for fire-proof deed boxes,
and other strong works in which solder would be inadmissible. It
is common in tin and copper works, but less so in iron and zinc,
which do not bend so readily.
Fig. 225 is a riveted joint, which is very commonly used in
strong iron plate and copper works, as in boilers, etc. ; generally
a rivet is inserted at each end, then the other holes are punched
through the two thicknesses with the punch 210, on a block of
lead. The head of the rivet is put within, the metal is flattened
around it, by placing the small hole of the riveting set 211 over
the pin of the rivet, and giving a blow ; the rivet is then clinched,
and it is finished to a circular form by the concave hollow in
another riveting set. When the works cannot be laid upen an
anvil or stake, a heavy hammer is held against the head of the
rivet to receive the blow ; in larger works the holes are all punched
before riveting, and the heads are left from the hammer.
Figs. 226 and 227 ; the plates a a, are punched with long mor-
tises, then b b, are formed into tenons, which are inserted and
riveted ; but in 227 the tenons have transverse keys to enable the
parts to be separated.
Fig. 228, the one plate makes a butt-joint with the other, and is
fixed by L formed rivets or screw-bolts s; the short ends are
generally riveted to the one plate, even when screwed nuts are
used. This mode is very common for cast-iron plates, as in stove
work.
Fig. 229 is the mode universally adopted for very strong ves-
sels, as for steam-boilers, in which the detached wrought-iron
plates are connected by angle-iron, rolled expressly for the pur-
pose, (see /, Fig. 27, p. 81). The rivet holes are punched in all the
four edges, by powerful punching engines furnished with travel-
ing stages and racks, which insure the holes being in line, and
equidistant, so that the several parts when brought together may
exactly correspond. The rivet r, which may be compared to a
short stout nail is made red-hot, and handed by a boy to the man
within 'the boiler, who drives it in the hole ; he then holds a heavy
hammer against its head, whilst two men quickly clench or burr
it up from without : between the hammering, and the contracting
of the metal in cooling, the edges are brought together into most
intimate and powerful contact. Bolts and nuts b, may be used to
allow the removal of any part, as the man-hole of the boiler.
For the curved parts of the boilers, the angle iron is bent into
corresponding sweeps, and for the corners of square boilers, the
angle iron is welded together to form the three tails for the re-
spective angles or edges which constitute the solid corner : this
when well done, is no mean specimen of welding.
294
THE PRACTICAL METAL-WORKER'S ASSISTANT.
Figs.
230
231
232
233
Tt frequently happens tbat several plates are required to be
joined together to extend their dimensions, or that the edges of
one plate are united as in forming a tube ; these joints are arranged
in the figures 230 to 240, similarly to those for angles previously
shown, from which they differ in several respects.
Fig. 230 is the lap- joint, employed with solder for tin plates,
sheet lead, etc., and for tubes bent up in these materials.
Fig. 231, the butt-joint, is used for plates and small tubes of the
various metals ; united with the hard solders they are moderately
strong, but with tin solder the junctions are very weak from the
limited measures of the surfaces.
Fig. 232 is the cramp-joint : the edges
are thinned with the hammer, the one is
left plain, the other is notched obliquely
with shears, from one-eighth to three-
eighths of an inch deep ; each alternate
cramp is bent up, the others down for
the insertion of the plain edge ; they are
next hammered together and brazed,
after which they may be made nearly
flat by the hammer, and quite so by the
file. The cramp-joint is used for thin
works requiring strength, and amongst
numerous others for the parts of musical
instruments. Sometimes also 230 is fea-
ther-edged; this improves it, but it is
still inferior to the cramp -joint in
strength.
Fig. 233 is the lap-joint without sold-
er, for tin, copper, iron, etc. ; it is set
down flat with a seam-set, Fig. 209, and
used for smoke-pipes, and numerous
works not required to be steam or water-
tight.
... — , Fig. 234 is used for zinc works and
1 ... ^[ i others ; it saves the double bend of 233.
Fig. 235 is the roll-joint employed for
lead roofs, the metal is folded over a
wooden rib, and requires no solder ; the water will not pass through
this joint until it exceeds the elevation of the wood. The roll-
joint is less bent when used for zinc, as that material is rather
brittle ; the laps merely extend up the straight sides of the wooden
roll, and their edges are covered by a half-round strip of zinc
nailed to the wood.
Fig. 236 is a hollow crease used for vessels and chambers for
making sulphuric acid ; the metal is scraped perfectly clean, filled
with lead heated nearly to redness, and the whole are united by
burning, with an iron heated also to redness. Solder which con-
tains tin would be acted upon by the acid, whereas until the acid
238
239
240
WORKS IN SHEET METAL. 295
is very concentrated, the lead is not injured ; this method is how-
ever now superseded by the mode of autogenous soldering. The
concentration of sulphuric acid and some other chemical prepara-
tions, is performed in vessels made of platinum.
Figs. 237 and 238 are very commonly employed either with
rivets or screw-bolts ; the latter joint is common in boilers, both
of copper and iron, and also in tubes ; copper works are frequently
tinned all over the rivets and joints, to stop any minute fissures.
Fig. 237 is the flange-joint for pipes.
Fig. 239, with rivets, is the common mode of uniting plates of
marine boilers, and other works required to be flush externally.
Fig. 240 is a similar mode, used of late years for constructing the
largest iron steam-ships ; the ribs of the vessels are made of T iron,
varying from about four to eight inches wide, which is bent to the
curve by the employment of very large surface-plates cast full of
holes, upon which the wood model of the rib is laid down, and a
chalk mark is made around its edge. Dogs or pins are wedged at
short intervals in all those holes which intersect the curve ; the rib,
heated to redness in a reverberatory furnace, is wedged fast at one
end, and bent round the pins by sets and sledge-hammers, and as
it grows or yields to the curve, every part is secured by wedges
until the whole is completed.
The following method of constructing metallic boats, invented by
Mr. Francis, of the Novelty Works, New York, is taken from Har-
per's New Monthly Magazine.
In many cases of distress and disaster befalling ships on the
coast, it is not necessary to use the car, the state of the sea being
such that it is possible to go out in a boat, to furnish the necessary
succor. The boats, however, which are destined to this service
must be of a peculiar construction, for no ordinary boat can live a
moment in the surf which rolls in, in storms, upon shelving or
rocky shores. A great many different modes have been adopted
for the construction of surf-boats, each liable to its own peculiar
objections. The principle on which Mr. Francis relies in his life
and surf-boats, is to give them an extreme lightness and buoyancy,
so as to keep them always upon the top of the sea. Formerly it
was expected that a boat in such a service, must necessarily take
in great quantities of water, and the object of all the contrivances
for securing its safety, was to expel the water after it was admitted,
In the plan now adopted the design is to exclude the water alto-
gether, by making the structure so light and forming it on such a
model that it shall always rise above the wave, and thus glide
safely* over it. This result is obtained partly by means of the model
of the boat, and partly by the lightness of the material of which it
is composed. The reader may perhaps be surprised to hear, after
this, that the material is iron.
Iron — or copper, which in this respect possesses the same proper-
ties as iron — though absolutely heavier than wood, is, in fact, much
lighter as a material for the construction of receptacles of all kinds.
296
THE PRACTICAL METAL-WORKER^ ASSISTANT.
on account of its great strength and tenacity, which allows of its
being used in plates so thin that the quantity of the material em-
ployed is diminished much more than the specific gravity is in-
creased by using the metal. There has been, however; hitherto a
great practical difficulty in the way of using iron for such a pur-
pose, namely, that of giving to these metal plates a sufficient stiff-
ness. A sheet of tin, for example, though stronger than a board,
that is, requiring a greater force to break or rupture it, is still very
flexible, while the board is stiff. In other words, in the case of a
thin plate of metal, the parts yield readily to any slight force, so far
as to bend under the pressure, but it requires a very great force to
separate them entirely ; whereas in the case of wood, the slight force
is at first resisted, but on a moderate increase of it, the structure
breaks down altogether. The great thing to be desired therefore,
in a material for the construction of boats, is to secure the stiffness
of wood in conjunction with the thinness and tenacity of iron.
This object is attained in the manufacture of Mr. Francis's boats by
plaiting or corrugating the sheets of metal of which the sides of the
boat are to be made. A familiar illustration of the principle on
which this stiffening is effected is furnished by the common table
waiter, which is made usually, of a thin plate of tinned iron,
stiffened by being turned up at the edges all around — the upturned
part serving also at the same time the purpose of forming a
margin.
The platings or corrugations of the metal in these iron boats
pass along the sheets, in lines, instead of being, as in the case of the
waiter, confined to the margin. The idea of thus corrugating or
Fig. 241.
WORKS IN SHEET METAL. 297
plaiting the metal was a very simple one ; the main difficulty in
the invention came, after getting the idea, in devising the ways
and means by which such a corrugation could be made. It is a
curious circumstance in the history of modern inventions that it
often requires much more ingenuity and effort to contrive a way
to make the article when invented, than it did to invent the article
itself. It was, for instance, much easier, doubtless, to invent pins,
than to invent the machinery for making ' pins.
The machine for making the corrugations in the sides of these
metallic boats consists of a hydraulic press and a set of enormous
dies. These dies are grooved to fit each other, and shut together ;
and the plate of iron which is to be corrugated being placed be-
tween them, is pressed into the requisite form, with all the force
of the hydraulic piston — the greatest force, altogether; that is ever
employed in the service of man.
The machinery referred to will be easily understood by the above
engraving. On the left are the pumps, worked, as represented in
the engraving, by two men, though four or more are often required.
By alternately raising and depressing the break or handle, they
work two small but very solid pistons which play within cylinders
of corresponding bore, in the manner of any common forcing-pump.
By means of these pistons the water is driven in small quantities,
but with prodigious force, along through the horizontal tube seen
passing across, in the middle of the picture, from the forcing-pump
to the great cylinders on the right hand. Here the water presses
upward upon the under surface of pistons working within the great
cylinders, with a force proportional to the ratio of those pistons
compared with that of one of the pistons in the pump. Now the
piston in the force-pump is about one inch in diameter. Those in
the great cylinders are about twelve inches in diameter, and as there
are four of the great cylinders the ratio is as 1 to 576. Areas
being as the squares of homologous lines, the ratio would be, mathe-
matically expressed, la : 4x 122=1 : 4 x 144=1 : 576. This is a
great multiplication, and it is found that the force which the men
can exert upon the piston within the small cylinder, by the aid of
the long lever with which they work it, is so great, that when multi-
plied by 576, as it is by being expanded over the surface of the
large pistons, an upward pressure results of about eight hundred
tons. This is a force ten times as great in intensity as that exerted
by steam in the most powerful sea-going engines. It would be
sufficient to lift a block of granite five or six feet square at the base,
and as high as the Bunker Hill Monument.
Superior, however, as this force is, in one point of view, to that
of steam, it is very inferior to it in other respects. It is great, so
to speak, in intensity, but it is very small in extent and amount. It
is capable indeed of lifting a very great weight, but it can raise it
only an exceedingly little way. Were the force of such an engine
to be brought into action beneath such a block of granite as we
liave described, the enormous burden would rise, but it would rise
298 THE PRACTICAL METAL- WORKER'S ASSISTANT.
•
by a motion almost inconceivably slow, and after going up perhaps
as high as the thickness of a sheet of paper, the force would be
spent, and no further effect would be produced without a new ex-
ertion of the motive power. In other words, the whole amount of
the force of a hydraulic engine, vastly concentrated as it is, and
irresistible, within the narrow limits within which it works, is but
the force of four or five men after all ; while the power of the
engines of a Collins' steamer is equal to that of four or five thousand
men. The steam-engine can do an abundance of great work ; while,
on the other hand, what the hydraulic press can do is very little in
amount, and only great in view of its extremely concentrated
intensity.
Hydraulic presses, before the introduction of D. Dick's anti-fric-
tion press, were often used, in such cases and for such purposes as
require a great force within very narrow limits. The indentations
made by the type in printing the pages of Harper's Magazine, are
taken out, and the sheet rendered smooth again, by hydraulic
presses exerting a force of twelve hundred tons. This would make
it necessary for us to carry up our imaginary block of granite a
hundred feet higher than the Banker Hill Monument to get a load
for them.
There are nine of these presses in the printing-rooms of Harper
and Brothers, all constantly employed in smoothing sheets of paper
after the printing. The sheets of paper to be pressed are placed
between sheets of very smooth and thin, but hard pasteboard, until
a pile is made several feet high, and containing sometimes two
thousand sheets of paper, and then the hydraulic pressure is applied.
These presses cost, each, from twelve to fifteen hundred dollars.
In Mr. Francis's presses, the dies between which the sheet of iron
or copper are pressed, are directly above the four cylinders which
we have described, as will be seen by referring once more to the
drawing. The upper die is fixed — being firmly attached to the top
of the frame, and held securely down by the rows of iron pillars on
the two sides, and by the massive iron caps, called platens, which
may be seen passing across at the top, from pillar to pillar. These
caps are held by large iron nuts which are screwed down over the
ends of the pillars above. The lower die is movable. It is attached
by massive iron work to the ends of the piston-rods, and of course
it rises when the pistons are driven upward by the pressure of the
water. The plate of metal, when the dies approach each other, is
bent and drawn into the intended shape by the force of the pressure,
receiving not only the corrugations which are designed to stiffen
it, but also the general shaping necessary, in respect to swell and
curvature, to give it the proper form for the side, or the portion of
a side, of a boat.
It is obviously necessary that the dies should fit each other in a
very accurate manner, so as to compress the iron equally in every
part. To make them fit thus exactly, massive as they are in mag-
nitude, and irregular in form, is a work of immense labor. They
WORKS IX SHEET METAL. 209
are first cast as nearly as possible to the form inten led, but as such
castings always warp more or less in cooling, there is a great deal
of fitting afterwards required, to make them come rightly together.
This could easily be done by machinery if the surfaces were square
or cylindrical, or of any other mathematical form to which the
working of machinery could be adapted. But the curved and
winding surfaces which form the hull of a boat or vessel, smooth
and flowing as they are, and controlled, too, by established and
well-known laws, bid defiance to all the attempts of mere mechanical
motion to follow them. The superfluous iron, therefore, of these
dies, must all be cut away by chisels driven by a hammer held in
the hand ; and so great is the labor required to fit and smooth and
polish them, that a pair of them costs several thousand dollars before
they are completed and ready to fulfil their function.
The superiority of metallic boats whether of copper or iron,
made in the manner above described, over those of any other con-
struction, is growing every year more and more apparent. They
are more light and more easily managed, they require far less
repair from year to year, and are very much longer lived. When
iron is used for this purpose, a preparation is employed that is
called galvanized iron. This manufacture consists of plates of iron
of the requisite thickness, coated on each side, first with tin, and
then with zinc ; the tin being used simply as a solder, to unite the
other metals. The plate presents, therefore, to the water, only a
surface of zinc, which resists all action, so that the boats thus made
are subject to no species of decay. They can be injured or de-
stroyed only by violence, and even violence acts at a very great
Disadvantage in attacking them. The stroke of a shot, or a con-
cussion of any kind that would split or shiver a wooden boat so as
to damage it past repair, would only indent, or at most perforate,
an iron one. And a perforation even, when made, is very easily
repaired, even by the navigators themselves, under circumstances
however unfavorable. With a smooth and heavy stone placed
upon the outside for an anvil, and another used on the inside as a
hammer, the protrusion is easily beaten down, the opening is
closed, the continuity of surface is restored, and the damaged boat
becomes, excepting, perhaps, in the imagination of the navigator,
as good once more as ever.
Metallic boats of this character were employed by the party under
Lieut. Lynch, of the U. S. Navy, now a traitor to his country, in
making their voyage to the Dead Sea. The navigation of the stream
was difficult and perilous in the highest degree. The boats were
subject to the severest possible tests and trials. They were impelled
against rocks, they were dragged over shoals, they were swept
down cataracts and cascades. There was one wooden boat in the
little squadron; but .this was soon so strained and battered that it
could no longer be kept afloat, and it was abandoned. The metallic
boats, however, lived through the whole, and finally floated in peace
on the heavy waters of the Dead Sea, in nearly as good a condition
as when they first came from Mr. Francis's dies.
I
300 THE PRACTICAL METAL-WORKER'S ASSISTANT.
The seams of a metallic boat will never open by exposure to tho
sun and rain, when lying long upon the deck of a ship, or hauled up
upon a shore. Nor will such boats burn. If a ship take fire at
sea, the boats if of iron, can never be injured by the conilagation.
Nor can they be sunk. For they are provided with air chambers
in various parts, each separate from the others, so that if the boat
were bruised and jammed by violent concussions, up to her utmost
capacity of receiving injury, the shapeless mass would still float
upon the sea, and hold up with unconquerable buoyancy as many
as could cling to her.
The principle on which these life-boats are made is found equally
advantageous in its application to boats intended for other pur-
poses. For a gentleman's pleasure-grounds, for example, how
great the convenience of having a boat which is always stanch and
tight — which no exposure to the sun can make leaky, which no
wet can rot, and no neglect impair. And so in all other cases
where boats are required for situations or used where they will be
exposed to hard usage of any kind, whether from natural causes
or the neglect or inattention of those in charge of them, this ma-
terial seems far superior to any other.
CHAPTER XVII.
WORKS IN SHEET METAL, MADE BY RAISING ; AND THE FLATTENING
OF THIN PLATES OF METAL.
CIRCULAR WORKS SPUN IN THE LATHE. — The former examples
have only called into action so small an amount of the malleable
or gliding property of the metals, that all the forms referred to
could be produced in pasteboard, a material nearly incapable of
extension or compression. The raised works now to be consid-
ered, call for much of this gliding or malleable action which may
be compared with the plastic nature of clay as an opposite extreme.
Thus a lump of clay is thrown on the potter's horizontal lathe, a
touch of the fingers shapes it into a solid round lump, the potter
thrusts his clenched hand into the centre, and it raises in form
something like a basin ; by applying the other hand outside to
prevent the material from spreading, it will rise as an irregular
hollow cylinder, and a gentle pressure from without, and a sustain-
ing pressure from within, will gather up or contract the clay into
the narrow mouth suited to a bottle, and which is made somewhat
in this manner almost by the fingers alone.
A similar and parallel application, due to the malleability of the
metals, and one which also requires the turning-lathe, is very ex-
WORKS IN SHEET METAL.
301
tensively practised: namely, the art of "spinning or burnishing to
form" thin circular works in several of the ductile metals and
alloys, as for teapots, plated candlesticks, the covers of cups and
vessels, the bell mouths of musical instruments, and numerous
other objects required in great numbers, and of thin metals. Plated
candlesticks are thus formed of several parts soldered together, or
retained in position by the fittings of their edges, the whole being
strengthened by a central wire, and by filling the entire cavity
with a resinous cement. The Figs. 242 and 248 are intended to
show the mode of spinning the body of a Britannia metal teapot
from one unperforated disk of metal.
The wooden mould or chuck a, Fig. 242, is turned to the form
of the lower part of the teapot, and a disk of metal b, is pinched
tight between the flat surfaces of a and c, by the fixed centre screw
d of the lathe, so that a, b, and c, revolve with the mandrel : and
now by means of a burnisher e, which is rested against a pin in the
lathe rest, as a fulcrum, and applied near the centre of the metal ;
and a wooden stick /, held on the opposite side to support the
edge, the metal is rapidly bent or swaged through the successive
forms 1, 2, 3, to 4, so as to fit close against the curved face of the
block and to extend up its cylindrical edge.
The mould a is next replaced by g, Fig. 243, a plain cylindrical
block of the diameter of the intended aperture. One of various
forms of burnishers (h, i, some bent, others T form, and so on, the
surfaces of which are slightly greased) are used, together with the
hooked stick or rubber/, first to force the metal inwards, as shown
at 5, 6, 7, and also to curl up the hollow bead which stiffens the
mouth of the finished vessel, 9. Sometimes the moulds are made
of the entire form of the inside of the work, but of several pieces,
each smaller than the mouth ; so that when the central block is
first removed the others may be successively taken out of the
finished vessel, like the parts of a hat-block or of a boot-tree.
It is of importance during the whole process to keep the edge
302
THE PRACTICAL METAL-WORKER'S ASSISTANT.
Fig. 244.
exactly concentric and free from the slightest notches, for which
purpose it is occasionally touched with the turning tool during the
process of spinning. The operation is very pretty and expeditious,
and resembles the manipulation of the potter who forms a bottle
or vase with a close mouth in a manner completely analogous,
although the yielding nature of his material requires the fingers
alone, and neither the mould, stick, nor burnisher.
The lenses of optical instruments
are often fixed in their cells by simi-
lar means; a, Fig. 244, shows in
excess the form of the metal when
turned, and b the thin edge when
curled over the glass by means of a
burnisher applied whilst the ring re-
volves in the lathe.
Much of the cheap Birmingham jewelry is also spun in the
lathe, but in a different manner. For instance, to make such an
object as the ring represented black in Fig. 245, a steel mandrel is
turned upon a lathe to the same form as the ring, but less in
diameter. The metal is prepared as a thin tube, it is soldered and
cut into short pieces, each to serve for one ring, and. these are spun
into shape almost in an instant, between the arbor and the milling
tool or roller, as seen in the front view, Fig. 246. It is clear that
unless the arbor were smaller than the work, the latter from being
Fig. 245
246.
undercut could not be released. Sometimes only one broad mill-
ing tool is employed, at other times two or more narrow ones.
This process is most distinctly a modification of two rollers, which
travel by surface-contact instead of by toothed wheels/ and differs
but little from the embossing or matting rollers employed by jewel-
ers and others for long strips instead of rings. Extending the
same application to the milling-tool upon a solid body, such as
milled nut, the interior metal supplies the resistance given by the
arbor, in the last figure.
WORKS RAISED BY THE HAMMER. — In raising the metals by
the hammer, we have to produce similar effects to those in the
spinning process ; not however by the gradual and continued pres-
sure of a burnisher, on one circle at a time, but by circles of blows.
WORKS IN SHEET METAL. 303
applied much in the same order, and as far as possible with the
same regularity of effect.
The art consists, therefore, of two principal points. First, so to
proportion the original size and thickness of the metal disks thai
it shall exactly suffice for the production of the required object —
neither with excess of metal, which would have to be cut off with
shears and thrown aside, wasting a part both of the metal and
labor, nor with deficiency of metal, which would be nearly a total
loss. Secondly, that the work shall be produced with the smallest
possible number of Hows, which sometimes tend to thin, and at other
times to thicken the metal; whereas the finished works should
present a uniform thickness throughout, and which is, in many
cases, just that of the original metal when in the sheet.
For instance, a hollow ball six inches diameter is made of two
circular pieces of copper, each seven and a half inches diameter.
Now, calling the original circumference of the disk twenty-two and
a half inches, this line eventually becomes contracted to eighteen
inches, or the circumference of the ball, — although, at the same
time, the original diameter of the disk, namely, a line of seven and
a half inches, has become stretched to that of nine inches or the
girth of the hemisphere.
This double change of dimensions, accomplished by the mallea-
bility or gliding of the metal, occurs in a still more striking man-
ner in the illustration of spinning the tea-pot, in which the disk,
originally about one foot diameter, becomes contracted to two or
three inches only at the mouth. The precise nature of the change
is seen on inspecting Figs. 190 and 192 in connection with the
radiated pieces 191 and 193 required for the formation of such
polygonal vases, when bent up and soldered at their edges.
The same vases wrought to the circular figure from round plates,
either by spinning or by the hammer, would not require disks of
metal so large as the boundary circles in Figs. 191 and 193 ; as
the pieces between the rays would be entirely in excess, they
would cause the vessels to rise beyond their intended sizes, and
would require to be pared off. But the original disks for making
the vases should be of about the diameters of the inner circles, as
then the pieces d, beyond the inner circles, would be nearly equal
to the spaces e, within these circles, which would leave the vessel
of uniform thickness throughout, and without deficiency or excess
of metal, supposing the conversion to be performed with mathe-
matical truth.
The first and most important notion to be conveyed in reference
to raising works with the hammer, is the difference between those
which may be called opposed, or solid blows, that have the effect of
stretching or thinning the metal ; and those which may be called
unopposed, or hollow blows, that have less effect in thinning than
in bending the metal ; in fact, it often becomes thickened by hollow
blows, as will be shown.
For example, the hammer in Fig. 247 is directly opposed to the
304
THE PRACTICAL METAL-WORKER'S ASSISTANT.
face of the anvil, or meets it face to face, and would be said to give
a solid blow ; one which would not jar the hand grasping the
plate, were the latter ever so thick or rigid : and this blow would
thin the metal by its sudden compression between two hard sur-
faces, the face of the hammer being represented at f.
Figs. 247
249.
The hammer in Fig. 248 is not directly opposed to the anvil, or
rather to that point of it which sustains the work, consequently
this would be called a hollow blow, one which would jar the hand
were the plate thick and rigid ; and it would bend the plate partly
to the form of the supporting edge, by a similar exhibition of the
forces a, b, c, referred to in the diagrams, Figs. 213 to 216 ; not, how-
ever, by the quiet pressure therein employed, but by impact, or by
driving blows. The hand situated at a, Fig. 248, would be insuffi-
cient to withstand the blows of the hammer at c, but for the great
distance of a b, compared with b c, and the thin flexible nature of
the material.
From these reasons the coppersmith and others never require
tongs for holding the metal, the same as the blacksmith, except at
the fire, as in annealing and soldering ; in hammering thin works,
a constant change of position is required, and which can be in no
way so readily accomplished as by the exquisite mechanism given
us by nature, the unassisted hand. When, however, the works are
too rigid or too small to be thus held, the anvil is made to supply
the two points a, c, as in Fig. 249, and the blow of the hammer is
directed between them.
We will now trace the effects of solid and hollovj blows given
partially on a disk of metal a a, Fig. 250, supposed to be twelve
inches diameter ; first within a central circle c c, of three inches
diameter ; and then around the margin a b, to the width of three
inches, leaving the other portions untouched in each case ; the
thickness of the metal is greatly exaggerated to facilitate the
explanation.
The solid blows within the circle c c, would thin and stretch that
part of the metal, and make it of greater superficial extent ; but
the broad band of metal a c, would prevent it from expanding be-
WORKS IX SHEET METAL.
305
be C b
2*7
vond its original diameter, and therefore the blows would make a
central concavity, as in a cymbal, or like Fig. 251. And the more
blows that were given, either inside the bulge upon a flat anvil, or
outside the bulge upon an anvil or head of a globular form, the
more would the metal be raised, from its being thinned and ex-
tended ; and thus it might be thrown into the shape of a lofty
cone or sugar-loaf.
The hollow blows given within the same
limited circle would also stretch the metal
and drive it into the hollow tools employed,
such as Fig. 249 ; thus producing the same
effect as in 251, but by stretching the metal
as we should the parchment of a drum,
by the pressure of the hand in the centre,
or by a blow of the drum-stick.
The solid blows around the three-inch
margin, would thin the metal and cause it
to increase externally in diameter; but
the plate would only continue flat, as in
Fig. 252, if every part of the ring were
stretched proportionally to its increased
distance from its first position. Were the
inner edge towards b, thinned beyond its
due amount, its expansion, if resisted by
the strength of the outer ring a, would
throw part of the work into a curve, and
depress the metal, not as in the cymbal,
but in the form of a gutter as in Fig. 253 ;
it would however more probably happen, that the inner edge alone
of the marginal ring would be expanded, leaving the outer edge
undisturbed, and producing the coned figure, 254.
The Mlow blows given around the edge, as in Fig. 248, would
have the effect of curling up or raising the edge, first as a saucer
255, and then into a cylindrical form 256 ; provided that by the
skilful management of the hammering, the metal could be made to
slide upon itself without puckering, so as to contract the original
boundary circle of the disk or twelve inches, into six inches, or
the measure of the edge of the cylinder resulting from the drawing
in of the three-inch margin.
In this process the metal would become proportionally thickened
at the upper edge, because each little piece of the great circle, Fig.
257, when compressed into a circle of half the diameter, would
only occupy half its original le^th, as it could not be altogether
lost ; and the metal would therefore increase in thickness in a pro-
portional degree. The remainder of the circle serves for the time
as effectually, to compress the metal in the direction of the tangent,
as if the radii were the sides of an unyielding angular groove
dotted in Fig. 257 : this contraction produces in fact the same effect
as the jumping or upsetting by endlong blows in smith's- work.
20
806 THE PRACTICAL METAL-WORKERS ASSISTANT.
Theoretically, the thickness of the upper edge of the cylinder
would be doubled, and the lower edge would retain its original
thickness, as in 256 ; whereas in extending the margin of the disk
by solid blows as in Fig. 252, the thinned edge would be found to
taper away, also in a straight line, from the full thickness even to a
feather edge if sufficiently continued, but neither of these cases
would be admissible, as the general object is to retain a uniform
substance.
In equalizing the thickness of the cylindrical tube, Fig. 256, the
solid blows would thin the metal, but at the same time throw it
into a larger circle , it would then require to be again driven in-
wards, which would again slightly thicken it. So that in reducing
the metal to uniformity, two distinct and opposite actions are going
on; and upon the due alteration, combination, or proportioning
of which, will entirely depend the ultimate form : that is, whether
the metal be allowed to continue as a cylinder ; to expand or to
contract, either as a cone or as a simple curve ; or to serpentine in
in any arbitrary manner, according as the one or other action is
allowed to predominate with the gradual development. The treat-
ment of such works with the hammer, is unlike spinning the teapot,
at those parts of the work where the metal is folded down in close
contact with the solid revolving mould therein employed ; but in
completing the upper part on the small block, Fig. 243, the burn-
isher and the rubber may be considered equivalent to the two anta-
gonist forces, which ^ad the hammered vessel inwards, or outwards
at the will of the operator.
This subject is too wide to enable any thing more to be offered
than a few general features, and I shall therefore proceed to trace
briefly the practice in some examples.
Figs. 258 259.
Fig. 258 represents the first stage of making the half of a cop-
per ball; the metal is first driven with a mallet into a concave bed,
generally of wood, in which it is hastily gathered up to a sweep
of about the third part of a sphere, as a, a, Fig. 259 ; but this puck-
ers up the edge like a piece of fluted silk, or the serpentine margin
of many shells, in the manner represented at/// Fig. 260, which
is of twice the size of 259.
The next step is to remove- the flutes or puckers by means of
blows of the raising hammer, applied externally as indicated by
the black lines at h, Fig. 260; and in Fig. 261 are represented, on a
still more enlarged scale, the relative positions of the hammer,
WORKS IX SHEET METAL.
307
anvil, and work. Thus A represents the globular face of the
anvil, B the rounded edge of the raising hammer, which like the
pane of an ordinary hammer, stands at right angles to the handle,
and a 1, shows the work, a being the edge, and 1 the point of the
flute. The blows of the hammer are made to fall nearly on the
centre o, of the anvil, and at a small angle with the perpendicular,
the hand being on the side a. A few blows are given as tangents,
or directly across the point of the flute, and when it exceeds the
width of the hammer, oblique blows are given to restore the pointed
character, to be followed by other blows parallel with the first, as
shown at h, Fig. 260. These hollow blows cause the sides of the
flutes to slide into one another, almost as when two packs of cards,
placed like the ridge of a house, penetrate into each other and sink
down flat: in a manner somewhat resembling that by which the
original and extreme margin in Fig. 257, becomes, by the succes-
sive blows, contracted to the inner circle ; but in the present case
the plait slides down to the general curve of the spherical dish.
Figs. 260
If, however, the puckers of a large globe were entirely removed
by hollow blows, the central lines of the flutes would become
thickened, and therefore solid blows are mingled with them, or
rather the one blow partakes of the two natures. Thus from the
curvature and oblique position of the hammer, Fig. 261, its face is
solid at s, to that part immediately below it, but towards h, it
rather bends than thins; the flatter the curves of the two surfaces,
the greater the extent of the solid or thinning blows. The plaits
are not, however, entirely gathered up, as the dish a, a, Fig. 259,
always opens a little, from the mefal becoming stretched under the
treatment for removing the flutes.
Throwing the works into flutes as described is not imperative,
for the hemisphere might be entirely raised, as in the succeeding
step, by blows on the outer surface upon a convex tool dP head,
but the flutes quicken the process, and speedily give a concavity
which is convenient, as it makes the work hang better on the
rounded face of the anvil.
The outer curve a a, Fig. 259, p. 306, which represents the cop-
per dish when the puckers have been removed, will not be sent
into the hemispherical form, or the inner line d d, at one process,
but will progressively assume the curvatures b b, c c, and some-
308
THE PRACTICAL METAL-WORKER'S ASSISTANT.
times many others ; neither will the work be changed from the
curve a a, to that of b b, at one sweep, or as with the burnisher in
spinning even by one consecutive ring or wave. The hammer
must necessarily operate by successive blows arranged in circles,
the proximity of which circles will at length include within their
range the entire sweep a a, or b b, each of which is called a course:
and before proceeding from one course or sweep to the next, the
metal requires to be annealed.
Figs. 261 and 262 explain the transition or conversion from the
first sweep a, to the second sweep b ; the black lines represent the
metal after a circles of blows have been given. Fig. 262 shows
the narrow edge of the raising-hammer, in the act of descending
upon the centre of the head or stake, and as a tangent to the circle ;
it first throws in a little rim at 1, which connects the new and old
sweeps by a curve or ogee: then another little circle 2, will be si mi-
Figs. 262
a b n p
larly gathered in, then 3, 4, 5, and so on, up to the edge. Now
the artifice consists in making the intervals both of the great
sweeps, a, 6, c, Fig. 259, and of the little waves 1, 2, 3, of Fig. 262,
as large as practicable, provided they do not cause the exterior
metal to pucker or become in plaits, as this would endanger its
ultimately cracking at those places, where the metal might have
become plaited.
In thus raising-in the metal, it necessarily becomes thickened
from its contraction in diameter, but as in Fig. 261 the hammer at
h, gives a hollow blow and bends, whilst the part s, gives a solid
blow and thins, the two effects are thus combined ; and when they
are duly proportioned, by a hammer more or less round, and blows
more or less oblique, the true thickness as well as the desired
change of figure are both obtained.
It is easier to get the hemisphere by a little excess of thinning,
or by a superfluity of blows : so that the less skilful workman will
use a piece of copper of seven inches diameter, with additional
blows, for a six inch hemisphere; but the more' skilful will take a
piece of seven and a half inches diameter, and obtain the work
with less labor. Occasionally, when the work is common and
WORKS IN SHEET METAL. 309
thin, from three to six hemispheres or other pieces are hollowed
together, the outer piece is cut as a hexagon or octagon, and its
angles are bent over to embrace the inner pieces, before the pro-
cess of hollowing is begun, and which scarcely consumes more
time than for one only. This is a general practice in hollowing tin-
works, such as the covers of sauce- pans, as the number of thick-
nesses divide the strength of the blows ; the several pieces are then
twisted round at intervals, so as to arrange them in a different
order, which mixes the little imperfections, and tends to their
mutual correction : the raising process represented in Fig. 262 is
also performed upon two or three pieces at a time, when they are
sufficiently thin to permit it.
One of the most conspicuous and remarkable examples of raised
works is the ball and cross of St. Paul's Cathedral, London. The
old ball consisted of sixteen pieces riveted together ; the present,
also 6 feet in diameter and J inch thick, was raised in two pieces
only, and may therefore be considered to mark the improvement
in the coppersmith's art in making large works, such as sugar-
pans, stills, etc.
The metal was first thinned and partly formed under the tilt-
hammer at the copper-mills, or sunk in a concave bed ; the raising
was effected precisely as explained in Fig. 262, and with hammers
but a little larger than usual ; the two parts were riveted together
in their place, and the joint is concealed by the ornamental band.
All the work is modern, and is mostly hammered up, except the
cast gun-metal consoles beneath the ball, which formed part of the
original metallic edifice; a name to which it is justly entitled, the
height being 29 feet, and the weight of copper 3J tons. The new
ball and cross are strengthened by a most j udicious inner framing
of copper and wrought-iron bars, stays, bolts, and nuts, extending
through the arms and downwards into the building; thus adding
about 2 tons of iron to the load of copper, and to the 38 ounces of
gold used in its decoration.
Having conveyed the full particulars for raising a hemispherical
shape, the modifications of treatment required for various other
forms will be sufficiently apparent. Thus, below the dotted lines
a df in Fig. 263 the sweeps are exactly the same as in Fig. 259,
but the metal rises higher from having been originally larger ; in
the courses g h, it is first kept rather thicker on the edge, and to-
wards the conclusion, it is thinned on the edge to the common
substance, and curled over by hollow blows from within, although
the whole figure might be produced by external blows, but which
would be a more tedious method.
On the other hand, by the continuance of the raising in, ex-
plained by diagram 262, the metal would be gathered into a smaller
diameter through the steps i, j, k, I, in the latter of which the metal
would become thickened, unless the solid or thinning blows were
allowed to predominate. If enough metal had been given in the
first instance, when the mouth had been contracted as to the form
81 0 THE PRACTICAL
of a teapot, it might be extended upwards as a cylindrical neck,
in the manner explained in Fig. 256, and curled over at the top,
as on the opposite side of Fig. 263. at h.
To lessen the labor of raising works from a single flat plate,
soldering is sometimes resorted to ; thus the teapots, Figs. 190 and
192, page 284, might be made in two dished pieces, and soldered
at the largest diameter ; the lofty vase or coffeepot, Fig. 194, could
be made from a cylinder of midway diameter soldered up the side,
the bulge being set-out by thinning the metal, and the contraction
above being drawn-in by hollow blows.
Vases in the shape of an earthen oil jar, or of the line I d n,
Fig. 263, could be made from a cone such as o p, with a bottom
soldered in ; these preparations would save the work of the ham-
mer, although such forms, and others far more difficult, could be
raised entirely by the hammer from a flat piece of metal.
Should any of the above vessels require a solid thickened edge
or lip, beyond that which would result from the drawing-in of the
metal, it would be necessary to select a piece of metal of smaller
diameter but thicker, and to retain the margin of the full thick-
ness by directing all the blows within the same ; sometimes, on
the other hand, works require to be thinned on the edge ; these
are then cut out proportionally smaller than their intended sizes,
as illustrated by the following example, which is considered the
most difficult of its kind.
The bell of a French horn, together with the first coil of the
tube, are made of a flat strip of metal about 4 feet long and 2
inches wide; for making the bell of the instrument, there is an
enlargement at one end of the strip, in the form of the funnel
piece 189, and of the width of 16 to 22 inches, the smaller piece
being adopted when the bell is required to be very thin. The
narrower piece of metal, when first bent up, much resembles the
butt end of a musket, terminating in a small tube ; the metal is
united and soldered down the edge with a cramp or dovetail joint,
Fig. 232 ; it is next thrown into a conical form of about five inches
diameter, and expanded from within, first with blows of a wooden
mallet upon a wooden block, and then with those of a hammer on
iron stakes.
When nearly finished, or about one foot diameter, it is ham-
mered very accurately upon a cast-iron mould turned exactly to
the form of the Veil, which is thus rendered much thinner than
the general substance, and remarkably exact; the band containing
the wire for stiffening the edge of the bell is attached by dexterous
hammering, and without solder. To bend the tube to the curve
^without disturbing its circular section, it is filled with a cement,
principally pitch, which allows the tube to be bent to the scroll of
the instrument, without suffering the metal to be puckered or dis-
turbed from its true circular section ; and in bencting similar tubes
to smaller curves, they are filled with lead. These materials serve
as flexible an 1 fusible supports, which are easily removed when
no longer required.
WORKS IN SHEET METAL.
311
Should any of the raised works have ornamental details', such
as concave or convex flutes, or other mouldings, they wo aid be
mostly overlooked until the general forms had been given ; and
then every little part would be proceeded with upon the same
principles of solid and hollow blows. Each of the series of flutes
would be first slightly developed all around the object, then more
fully, and so on until the completion ; when, however, the details
are so large, as to form what may be considered integral parts, it
is necessary to prepare for them at an earlier stage.
Thus, to take an excellent familiar example, let Fig. 264 repre-
sent plans, 265 sections, and 266 elevations of jelly moulds many
of which require the greatest skill of the coppersmith. The gen-
eral outline is that of a cylinder abed, upon a larger cylinder ef
g h, as a base. The twelve large and deeply indented flutes or
finials, rise perpendicularly to a great height from the plane sur-
faces a c and e b, and yet the whole is hammered out of one flat
plate.
Figs. 254 285 26P.
1 1
a c
.. X J
j
>\
o a ••
\
Is.
1
The first step is to raise the summits of the flutes i or k, pre-
paratory to the general formation of the upper cylinder abed,
and then the two are worked up together, leaving for a time the
expanded base e f g h, but ultimately the whole receive a general
attention in common. If the flutes were polygonal, and terminated
in ornaments like spires or finials, as at k, they would be first
treated as if for the more simple or generic form i, and t}ie details
would be subsequently produced.
The skill called for in such works is greatly enhanced by the
attention which is required to preserve a nearly uniform thickness
in the metal, notwithstanding the apparent torture to which it is
submitted ; and this is only endured in consequence of a frequent
recurrence to the process of annealing, which reinstates the mallea-
ble property.
In cases of extensive repetition, or where large numbers of any
specific shape are required, expensive dies of the exact forms are
employed ; but these are only applicable to objects in small relief,
and to those in which the parts are not quite perpendicular. Dies
would be entirely inapplicable to objects such as the jelly moulds,
Fig. 265, although a common notion exists that they are rapidly
312 THE PRACTICAL METAL-WORKER'S ASSISTANT.
made by that method, but which is in general utterly impossible
when such objects are made in one piece. In all such cases the
metal has to undergo the same bend ings and stretchings between
the dies as if worked by the hammer, and which unless gradually
brought about are sure to cut and rend the metal. The pro-
duction of many such forms with dies is therefore altogether im-
practicable.
Figs. 267 268.
i s
For example, the pattern or moulding, 2, Fig. 267, is only in
small relief, and yet the flat piece of metal a would be cut in two
or more parts if suddenly compressed between the dies A B, as
the edges i j would first abruptly bend and then cut the metal,
without giving it the requisite time to draw in, or to ply itself
gradually to the die, beginning at the centre as in the process of
hammering.
In Fig. 268 the successive thicknesses obliterate the effect of the
acute edges of the bottom die B ; the face and back of every thick-
ness differ, as although parallel they are not alike, but they become
gradually less defined, so that in Fig. 268 the top die A requires
nothing more than a flowing line with slight undulations. There-
fore, when two or three dozen plates are inserted between the dies
A B, the transition from a to 2 is so gradual that the metal can
safely proceed from a to b, from b to c, and so on, and it will be
progressively drawn in and raised without injury. When one or
two pieces alone are required, they are blocked-down to fit the mould
by laying above them a thick piece of lead, which latter is struck
with the mallet or hammer. By the yielding resistance the lead
opposes, the thin metal is drawn into the die with much less risk
of accident than if it were subjected to the blows without the in-
tervention of the lead.
In producing many pieces, however, one piece, a, is added at the
top, between every blow, and one piece, 2, is also removed from the
bottom. Occasionally, two, three or more are thus added and re-
moved at one time, and generally, as the concluding step, every
piece is struck singly between the dies, such as Fig. 267, which
exactly correspond. In general the process of annealing must be
also resorted to once or more frequently during the transition from
a to 2. For the best works the bottom die is mostly of hardened
steel, sometimes of cast-iron or hard brass. The top die is also
of hardened steel in the best works, but in very numerous cases
WORKS IN SHEET METAL. 313
lead is used, from the readiness with which it adapts itself to the
shape required.
Stamping is very common for many works in brass, but which
would be inapplicable if the pieces had perpendicular and lofty
sides, as in Fig. 265, page 311. Such lines, although rounded by
the successive thicknesses of metal, would still present perpendicu-
lar sides, and therefore render this mode of treatment with dies
impracticable, without reference to cost. Thimbles are raised at
five or six blows, between as many pairs of conical dies successively
higher, but the metal requires to be annealed every time.
PECULIARITIES IN THE TOOLS AND METHODS. — Before con-
cluding the remarks on raised works, it may be desirable to revert
to some of the principal and distinguishing features of the tools
employed in these arts. As a general rule, it will be observed that
all these manifold shapes are the more quickly obtained the more
nearly the various tools assimilate to the works to be wrought.
For instance, the several dies and swage tools quickly and accu-
rately produce mouldings of the specific forms of the several pairs
of dies ; but it is utterly impossible to extend this method to all
cases, and the progressive changes required, from the flat disk, the
cylinder or cone, as the case may be, to the finished object ; and
therefore certain ordinary forms of tools can alone be employed,
and they are continually changed as the work proceeds.
For hollow works with contracted mouths, the inner tools are
required gradually to decrease in bulk and to increase in length,
in order to enter the cavities ; but they can be rarely the exact
counterparts of the transient forms of the works, nor is it always
desirable they should be so. The tools are often required to be
bent at the end, to extend within a shoulder or gorge. The small
stake in the tool, Fig. 203, is an example of this ; the dotted line
represents the work, such as the perforated cover of a cylinder, or
the top of a teakettle. The strong wrought-iron arm or horse,
Fig. 203, carries the small steel tools, and which latter may be also
fixed by their shanks either in the bench or vice, according to
circumstances.
There are many curious circumstances respecting the modifica-
tion of the materials for, as well as the forms of, the hammers and
anvils, if the use of these terms may be extended to the various
contrivances, by the action and re-action of which thin metal works
are produced ; and the concluding examples are advanced to bring
some of these peculiarities of method into notice.
The plated metals have so thin a coating of silver, that they re-
quire more expert hammering than similar works in solid silver,
otherwise the removal of the bruises left by the hammer, by scrap-
ing and polishing, might wear through the silver and show the
copper beneath. The bruises are therefore driven to the copper
side, by hammering upon the silver or the face, with a very smooth
planishing hammer, and covering the anvil or bottom tool with
cloth. On account of the elasticity thus given, the blows become
314 THE PRACTICAL METAL-WORKER'S ASSISTANT.
so far hollow that all the little bruises descend to the copper side,
or that which is exposed to the cloth, and the face becomes per-
f'ectly smooth.
When the inside of a vessel is required to be smooth, it is the
hammer that is covered with cloth, stretched over it by an iron
ring, and the polished stake or head within the vessel is left uncov-
ered ; and in those cases in which the work is required to be good
on both sides, the faces both of the hammer and anvil are each
muffled ; this gives them some of the elasticity of wooden tools,
but with superior definition of figure.
Plated works are generally furnished with an additional thick-
ness of silver at the part to be engraved with a crest or cipher, in
order that the lines may not penetrate to the copper; should it,
however, be requisite to remove the engraved lines for the substi-
tution of others, the following mode is resorted to.
The object is laid upon the anvil over a piece of sheet lead and
it is struck with a bare hammer upon the engraved lines ; these latter
are therefore hollow as regards the face of the hammer ; in conse-
quence of which, the re-action of the lead causes it to rise in ridges
corresponding with the engraved lines, and to drive the thin
plated metal before it. The device is thus in great measure oblit-
erated from the silver face and thrown to the copper side, so as to
leave much less to be polished out ; this ingenious method is ap-
propriately called reversing.
In making vases, such as Figs. 192 and 194, page 284, the metal
is first driven into concave wooden blocks with a wooden mallet, as
in Fig. 258, in order to gather up the metal into the fluted concave
260, but without making any sensible alteration in its thickness.
In the next stage of the work, metal tools are alone employed,
whether the object be made by raising-in with hollow blows, or by
setting-out with solid blows, as adverted to; and the sizes and
curvatures of the tools require to be accommodated to the changes
of the work.
Supposing the vases to have either concave or convex flutes,
ornamental details are now sketched with the compasses upon the
plain surface of the vase ; and if from the shape of the works
swage tools similar to Fig. 212, cannot be employed for raising
the projecting parts, they are snarled-up, by the method represented
in Fig. 269.
Thus at v are the jaws of the tail vice, in which the snarling-
iron s, is securely fixed : the extremity b, which is turned up, must
be sufficiently long to reach any part of the interior of the vessel,
but yet small enough to enter its mouth. The work is held firmly
in the two hands, with the part to be raised or set out exactly over
the end b ; and when the snarling-iron is struck with a hammer at
7i, the re-action gives a blow within the vessel, which throw the
metal out in the form of the end of the tool/whether angular,
cylindrical, or globular : except in small works, two individuals
are required, one to hold and the other to strike.
WORKS IX SHEET METAL.
315
Figure 270 shows the. last stage of the work prior to polishing;
thus in finishing the flutes and other ornaments after they are
snarled-up, the object is filled with a melted composition of pitch
and brick-dust — sometimes the pitch is used alone, or common
resin is added — the ornaments are now corrected with punches or
271.
chasing tools of the counterpart forms of the several parts ; some
portions of the metal are thus driven inwards, whilst those around
rise up from the displacement and reaction of the pitch. To avoid
injuring the lower surface of the work it is supported upon a sand-
bag b, like those used by engravers, and the perpendicular lines p,
denote the usual position of the chasing tool.
Works in copper and brass are sometimes filled with lead at the
time of their being chased, but the silversmiths and goldsmiths
are studious to avoid the use of this metal, as, if it gets into the
fire along with their works, it is very destructive to them.
Pitch and mixtures of similar kind, are constantly used in the
art of chasing in its more common acceptation ; from its adhesive
and yielding nature it is a most appropriate support, as it leaves
both hands at liberty, the left to hold the punch, the right for the
small hammer used in striking it.
The pitch-block, Fig. 271, is employed to afford the utmost
choice of position for works from the smallest size to those of six
or eight inches long. The lower part is exactly hemispherical, and
it is placed upon a stout metal ring or collar of corresponding
shape, covered with leather. The mass of metal makes a firm
solid bed to sustain the blows, and the ball and socket contact,
allows the work to assume every obliquity, and to be twisted
round to place any part towards the artist.
Large flat works in high relief are frequently sketched out and
commenced from the reverse face, the prominent parts of the sub-
ject being sunk into the pitch, which after a short time must be
melted away to allow the metal to -be annealed ; and this is fre-
quently required when the works are much raised. In the con-
cluding steps the artist works from the face side.
Many of the chased works are cast in sand moulds from metal
models, which have been previously chased nearly to the required
forms; the castings are first pickled to remove the sand coat, and in
such cases, chisels and gravers are somewhat used in removing the
useless and undercut parts.
316 THE PRACTICAL METAL-WORKER'S ASSISTANT.
Many ancient specimens of armor, gold and silver plate, vases
and ornaments, are excellent examples of raised, chased, an.d in-
laid and engraved works, both as regards design and execution.
In our own times, the Hungarian silversmith, Szentepeteri, has
produced a very remarkable alto-relievo in copper, taken from Le
Brun's picture of the battle of Arbela, in which some of the legs
of the horses stand out and are entirely in relief from the back-
ground.
The art of chasing may be considered as the sequal to that of
forging (that is, setting aside the employment of the red-heat), but
the various hammers and swage tools now dwindle into the most
diminutive sizes, and are required of as many shapes as may nearly
correspond with every minute detail of the most complex works.
Some of them are grooved and checkered at the ends, and others
are polished as carefully as the planishing hammers, that they may
impart their own degree of perfection and finish to the works ; in a
similar manner that the polish and excellence of coins and medals
are entirely due to that of the dies from which they are struck,
the chasing process being as it were a minute subdivision of the
action of the die itself.
THE PRINCIPLES AND PRACTICE OF FLATTENING THIN PLATES
OF METALS WITH THE HAMMER. — I have purposely reserved this
subject to be distinct, on account of its great general importance in
the arts, and have placed it last, in order that the various applica-
tions of the hammer might have been rendered comparatively
familiar ; for, although the plane surface may appear to be of more
easy attainment than many of the complex forms which have been
adverted to, such is by no means the case.
The methods employed are entirely different from that explained
at page 153, in reference to flattening thick rigid plates, which are
corrected by enlarging the concave side, with blows of the sharp rect-
angular edge of the hack-hammer, applied within the concavity. A
method which bears some analogy to that employed by the joiner in
straightening a board which is curved in its width, namely, the
contraction of its convex side by exposure to heat. In thin metal
plates neither of these modes is available, as the near proximity of
the two sides causes both to be influenced in an almost equal
degree by any mode of treatment.
Thin plates are flattened by means of solid and hollow blows,
which have been recently explained, but they require to be given
with considerable judgment ; and a successful result is only to be
obtained by a nice discrimination and considerable practice. All
therefore that can be here attempted is an examination of the prin-
ciple concerned, and of the general practice pursued ; as the pro-
cess being confessedly one of a most difficult nature, success is
only to be expected or attained by a strict and persevering regard
to principle.
As respects thin works, no figure is so easily distorted as the
true plane, and this arises from the very minute difference which
WORKS IN SHEET METAL. 317
exists between the span or chord of a very flat arch, and its length
measured around the curve. For example, imagining the span of
an arch to be one inch, and the height of the same to be one-twen-
tieth of an inch, the curve would be only about one 200th of an
inch longer than the span: and therefore, if any spot of one inch
diameter were stretched until, if unrestrained, it would become one
inch and one 200th in diameter, such spot would raise up as a
bulge one-twentieth of an inch high. This trivial change of mag-
nitude would be accomplished with very few blows of the ham-
mer, and much less than this would probably distort the whole
plate.
In general, however, there would be not one error only, but
several, the relationship of which would be more or less altered
with nearly every blow of the hammer ; thence arises the difficulty,
as the plane surface cannot exist so long as any part of the plate is
extended beyond its just and proportional size, and which it is a
very critical point to arrive at.
There is another test of the unequal condition of flat works be-
sides that of form, namely, their equal or unequal states of elasti-
city, and which is an important point of observation to the work-
man. For instance, if we suppose a plate of metal to be exactly
uniform in its condition, it will bend with equal facility at every
point, so that bending a long spring, or saw, will cause it to assume
a true and easy curve ; but supposing one part to be weaker than
the remainder, the saw will bend more at the weak part, and the
blade will become as it were two curves moving on a hinge. When
such objects are held by the one extremity and vibrated, the per-
fect will feel as a uniformly elastic cane ; the imperfect, as a cane
having a slight flawr which renders it weak at one spot ; and in
this manner we partly judge of the truth of a hand-saw, as in
shaking it violently by the handle, it will, if irregularly elastic,
lean towards the character of the injured cane, a distinction easily
appreciated.
Fig. 272.
A thin plate of metal can only be perfectly elastic, when it is
either a true plane or a true curve, so that every point is under the
same circumstances as to strength. Thus a hemisphere, as at a, 272,
possesses very great strength and rigidity owing to its convexity,
but as the figure becomes less convex it decreases gradually in
strength, and when it slides down to the plane surface, as at f, the
metal assumes its weakest form.
A nearly plane surface will necessarily consist of a multitude of
convexities or bulges varying in size and strength, connected by
318 THE PRACTICAL METAL-WORKERS ASSISTANT.
intermediate portions, which may be supposed to be plane surfaces ;
the whole may be considered as greatly exaggerated in the figure.
The bulged parts are stronger than the plane flat parts, it follows
that the bending will occur in preference at the plane or weak
parts of the plate, precisely as in the injured cane.
When the bulges are large but shallow, they flap from side to
side with a noise at every bending, as their very existence shows
that they cannot rest upon the neutral or straight line ; such parts
are said to be buckled, their ready change of position renders them
flaccid and yielding under the pressure of the fingers, and they are
therefore called loose parts, but at the same time it is certain that
they are too large.
On the contrary, those parts which are intermediate between the
bulges, feel tight and tense under the fingers, because they are
stretched in their positions and rendered comparatively straight,
by the strong edges of the bulged or convex parts : the flat portions
are the hinges upon which the bulged parts move, and such flat
parts are sensibly too small for their respective localities, the others
being too large.
Now, therefore, in prescribing the rule for the avoidance of these
errors, it is simply to treat every part alike, so that none may be
stretched beyond its proper size so as to become bulged, and thereby
to distort the whole plate. When the mischief has occurred, the
remedy is to extend all the too-small parts, or the hinges of the bulges
to their true size, so as to put every part of the plate into equal
tension, by allowing the bulged or too-large parts room to expand.
Uniform blows should be therefore directed upon all the straight
or too-small parts of the plate, the force and number of the blows
being determined by the respective magnitudes of the errors, and
the rigidity of the plate.
In flattening plates, the greater part of the work is done with
solid blows upon a true and nearly flat anvil ; the face of the ham-
mer is slightly round, and its weight and the force of the blows are
determined by the strength of the plate, the slighter plate requiring
more delicate blows, and being more difficult to manage. In the
commencement, the rectangular plate is hammered all over with
great regularity in parallel lines beginning from one edge ; it is
generally turned over and similarly treated on the other side. Cir-
cular plates are hammered in circular lines beginning from the
centre, that is supposing the plates of metal to be soft, and in about
the ordinary condition in which they are left by the laminating
rollers ; as the equable hammering gives a general rigidity, which
serves as a foundation for the correctional treatment finally pur-
sued. With a steel plate hardened in the fire, and which is already
fur more rigid than the soft plate, it is necessary to begin at once
upon the reduction of the errors and distortions, which usually
occur in the hardening and tempering.
The hammer should be made to fall on one spot with the uni-
formity of a tilt-hammer, the work being moved about beneath it.
WORKS IN SHEET METAL.
319
As, "however, the regularity of a machine is not to be expected from
the hand, it is scarcely to be looked for that the work shall be at
once flat. Whilst the errors are tolerably conspicuous or consider-
able, the man accustomed to the work will still keep the hammer
in constant motion, and will so shift the work, as to bring the tight
parts alone beneath its blows, hammering with little apparent con-
cern just around the margins of the loose parts, or at the foot of
every rise. As the plate becomes more nearly flat, it is necessary
to proceed more cautiously, and to hold the plate occasionally be-
tween the eye and the light to learn the exact parts to be enlarged ;
the straight-edge is also then resorted to.
In many works, especially in saws which require very great
truth, the elasticity is also examined ; this is frequently done by
holding the opposite edges of the plate between the fingers and
thumbs, and bending them at various parts. As previously ex-
plained, all the portions which, are technically called tight, or those
lines upon which the loose enlarged parts appear to move as on
hinges, are strictly the parts to be extended by gentle hammering.
For instance, supposing that in the plate, Fig. 273, there were only
Figs. 273
• 274.
one central buckle % the whole exterior portion would require to
be stretched, beginning from the base of the bulge : but it must be
remembered the extreme edges of the plate will yield with greater
facility than the more central parts, and therefore require some-
what fewer blows, as the blows are all given as nearly as possible
of the same intensity, and the number of them is the source of
variation.
If, as it is more to be expected, there are two or more loose parts,
such as a, and b c, the more quiescent part between them must be first
hammered, as working upon any loose or bulged part only magnifies
the evil. Where the intermediate space is narrow, as at d, less blows
will be needed, and such tight parts will soon, and sometimes very
suddenly, become loose from the two bulges melting into one. It
should be rather the general aim to throw the several small errors
into a large one, by getting the plate into one regular sweep ; dealing
the blows principally between the dotted lines, not carelessly so as
to increase the general departure from the plane surface, but with
an acute discrimination to lead all the defects in the same direction,
by making the plate as it 'were a part of a very great cylinder, as
at e or/, Fig. 274, but with as little curvature as possible.
320 THE PRACTICAL METAL-WORKER'S ASSISTANT.
When this is accomplished, and that the work is free from loose
parts, it is hammered on the rounding side, in lines parallel with
the axis of the imaginary cylinder ; so that in e the lines would be
parallel with the edge from which the rise commences, and in/, or
the plate which is bent diagonally, the lines of blows would be
necessarily oblique, although as regards the curvature, the same as
in e. The reason why any reduction of curvature should at all
result from this treatment (action and reaction being alike) is due
to the greater roundness of the hammer than the anvil ; the rounder
hammer effects the change more rapidly, but also the more indents
the work.
In a circular saw, the general aim is first to throw the minor
errors into one regular concavity, which may be supposed to extend
to b b in the imaginary section, Fig. 275, and then the margin a b
would be hammered in a proportional degree, to enlarge it until it
just allowed the interior sufficient room to expand to the plane
surface.
Fig. 275.
It may happen in the course of the hammering that from b to b
becomes loose, whilst the extreme edge a a is also loose, and that
the intermediate part towards b requires to be stretched. These
minor differences cannot be told alone by bending the plate with
the fingers, as errors frequently exist which are too minute to yield
to their pressure, and then the eye and straight-edge are conjointly
employed in the examination.
In a saw, the general aim is to leave the edge rather tight or
small, as then the small amount of expansion it acquires when at
work, from heat and friction, will enlarge the edge just sufficiently
to bring the saw into a state of uniform tension. Otherwise, if
before the saw is set to work the edge is fully large enough, when
expanded by the heat it is almost sure to become loose on the
edge, and to vibrate from side to side, without proper stability, so
as to produce a wide irregular cut, and make a flanking whip-like
noise, arising from the violent vibration of the buckled parts
of the plate in passing through the saw kerf; the sides of the
wood will then exhibit ridges like the ripple-marks on the sandy
shore.
In hammering all plates, preference should in the like manner
be given to keeping the edge rather small or stiff, to serve as a
margin or frame to the more loose parts within. It gives a degree
of stability somewhat as if the object had a thickened rim, and
when a rim really exists, the process of flattening is comparatively
easy.
If by undue stretching the edge is made too loose, the whole
piece becomes flaccid and very mobile, and we seem to lose the
WORKS IN SHEET METAL. *^/)> 321 .
governing power, or those retaining points by which the changed /,
of the plate are both influenced and rendered apparent. The edge
should be therefore always kept somewhat tight, from being pro-
portionally less hammered, especially as the edge more easily
admits of expansion than the inner part.
As a general rule, it may be said, that every part of the plate
which is straight and tense, whilst others are curved and flaccid,
denotes that every straight part is under restraint ; and that its
straightness is due to its being, as it were, stretched, either length-
way « or around its edges, by the other parts, which are too loose,
and therefore arched and also strong. In such cases, the straight
lines require to be extended in length, to allow sufficient room for
the curves to expand to their proportional sizes. This refers not
only to small local errors towards the inner part of the plate, as
explained by diagram, Fig. 273, p. 319 ; but should the one edge
of a plate be tolerably straight, whilst the opposite is loose and
flaccid, the rule also applies with equal truth, and the straighter
side must be hammered. In this case the curved side is as it were
a great bulge cut in two parts.
Should a circular saw have a sudden dent, such as at g, Fig. 275.
on the last page, standing the reverse way, and which may result
from its having rested upon a small lump of coke whilst in the
fire, the first blows will be given on the hollow side, between the
lines i i, to lessen the abruptness of the margin by stretching it to
the dotted curve, and then it will be driven downwards by violent
blows, to form a part of the general sweep or concavity. A little
time is gained by these driving blows over the mode of stretching
by the hammer.
The foregoing descriptions have all referred to solid blows, upon
the face of the hard anvil, but to expedite the process recurrence
is often had to blocking, which is only one application amongst
many others of a wooden anvil or block with a narrow flat-faced
hammer, such as Fig. 248. In this case the blows are to a certain
extent hollow, as the wood immediately beneath the hammer-face
yields to the blow, whereas the margin around the same does not.
Such blows are therefore unquestionably hollow, and bend with
very little stretching.
The blocking is considerably employed in saw-making after the
loose parts have been entirely removed, as the hollow blows cor-
rect any slight errors of figure, by bending alone, and with little
risk of stretching the plates, if the work be delicately performed.
Towards the conclusion, however, all the different modes of work
are required to be used in combination, as the true condition of
the plate is only the exact balancing of all the forces, or of the
tension of the several parts ; and it constantly happens that atten-
tion to one error causes a partial change and fluctuation throughout
the whole. It therefore requires great tact to know when to leave
the anvil for the block, and when to return to the anvil, and so on
alternately ; and also which side of the plate should be upwards
21
322 THE PRACTICAL METAL-WORKER'S ASSISTANT.
for the time, which particular points should be struck, and the
required force of the blows.
Of course, within certain limits, a thick plate is easier to hammer
than a thin one, as the latter is difficult from its excessive mobility ;
also a soft plate of iron is more difficult than a hard plate of steel,
although the latter requires more blows to produce the same effect ;
but when the works are very thick they become laborious, and the
difficulty always increases rapidly with the size of the plate.
Those who may desire to practise this art should therefore com
mence with a plate some 4, 6, or 8 inches square, and moderately
stout, and subsequently proceed to pieces larger and thinner. They
will also find some advantage in raising the anvil to within about
a foot of the eye, as the alterations can be then more easily seen
whilst the work lies on the anvil, and the effect of any predeter-
mined blows can be the better watched. One other observance is
essential, namely, patience ; as, although, the process is thoroughly
reducible to system, and no blow should be struck in vain, the
beginner will frequently find it necessary to pause, examine, and
consider, especially as the errors decrease ; whereas the accus-
tomed eye will follow the fluctuations of the plate almost without
intermission of the blows, and will also accomplish the task with
the fewest possible" number of blows, which is the great object.
Indeed it may happen from hammering some parts of a plate
excessively and improperly, that it is rendered so hard and rigid,
as to make its correction very tedious, or indeed nearly impossible
without previous annealing, as the plate might burst or crack from
the extension being carried beyond the safe limit of malleability.
As in raised works, the annealing is mostly done by a gentle red
heat ; but in hardened steel plates, a slight increase of temperature
barely sufficient to discolor the plate, will make a perceptible dif-
ference ; and this latter process is always the last step in making
a saw, in order to restore, by a gentle heat, the proper elasticity
which has been mysteriously lost in the grinding, poshing, and
hammering required in its manufacture.
CHPTER XVIII.
PROCESSES DEPENDENT ON DUCTILITY.
DRAWING WIRES, ETC. — The ductility of many of the metals
and alloys, or the quality which allows them to be drawn into
wires, is applied to a variety of curious uses in the manufacturing
arts, and the process may be viewed as the sequel to the use of
grooved and figured rollers ; but the ductile metals submit to this?
process with various degrees of perfection.
PROCESSES DEPENDENT ON DUCTILITY. 323
In drawing wire, the metal is first prepared to the cylindrical
form, either directly by casting, or between rollers with semicir-
cular grooves ; and the process is completed by pulling the metal
through a series of holes gradually less and less, made in a me-
tallic plate, by which the wire becomes gradually reduced in size,
and elongated ; but, as in rolling, the process of annealing must
be resorted to at proper intervals.
In general, the draw-plates are made of hardened steel, and
they are formed upon the same principle, whether for round,
square, or complex sections, either solid as wires, or hollow as
tubes ; the substance of the metal is partly kept back, as in a
wave, by a narrow ridge within the draw-plate, acting as a bur-
nisher.
The plates are generally made of hardened steel, or else of alloys
of partly similar nature, which allow the holes to be contracted
and repaired, by closing them with blows of a pointed hammer or
punch around the hole.
The holes for round wires are sometimes ground out from both
sides upon the same brass cone or grinder, the sides of which vary
in obliquity from 10 to 30 degrees, according to the metal to be
drawn ; for the sake of strength the ridge is mostly nearer to the
side on which the metal enters, and the sharp edgevis also removed,
either by wriggling the plate upon the grinder in order to round
the inside, or in any other manner.
The end of the wire is pointed, to enable it to be passed through
the hole, and it is then caught by a pair of nippers, themselves at
the extremity either of a chain, rope, toothed rack, or screw, by
which the wire is drawn through by rectilinear motion. The nip-
pers or dogs resemble very strong carpenters' pincers or pliers, the
handles of which diverge at an angle ; they are sometimes closed
by a sliding ring at the end of the strap or chain, which slides
down the handles of the nippers ; there are some other modifica-
tions, all acting upon the same principle, of qompressing the nip-
pers the more forcibly upon the wire the greater the draught. It
requires a proportionally strong support to resist the strain ; and
to avoid the fracture of the hardened steel draw-plate, it is usually
placed against a strong perforated plate of wrought-iron. In
manufactories where large quantities of wire are made, the wire is
more usually attached to the circumference of a reel, which is
made to revolve by steam or other power.
It is necessary often to anneal the wire, but no general rule can
be stated in respect to its recurrence ; and before resuming the
drawing process, the wire is invariably immersed in some acid
liquor or pickle, to remove the slight coating of oxide, which
would otherwise rapidly destroy the plates (as many of these me-
tallic oxides are used in polishing), in general some lubricating
matter is applied to reduce the friction, as beer-grounds, starch-
water or oil ; and for gold and silver, wax is generally used.
Most of the wire is drawn upon reels, and is therefore met with
324 1HE PRACTICAL METAL-WORKER'S ASSISTANT.
in circular coils, and it is necessary, in almost every case, to
straighten it before use. The soft annealed wires, such as the cop-
per wire used for bell-hanging, the soft iron binding -wire used in
soldering, and others, are stretched and straightened by fixing the
one end, and pulling the other with a pair of pliers ; or short pieces
of soft wire may be straightened by rolling them between two flat
boards.
So steel wire for making needles is straightened by rolling or
rubbing: it is cut up in lengths of 4 or 5 inches, and arranged in
cylindrical bundles, within iron hoops of 4 inches diameter ; the
rubber is a bar of cast-iron, about two feet long, narrow enough to
lie between the rings.
The hard-drawn and unannealed wires, used for making pins,
bird-cages, blinds, and numerous other wire- works, are too elastic
to yield to the above methods, and Fig. 276 represents the mode
employed to take the spring out of them, or in other words, to
straighten these hard wires. The coil of wire on the reeiyj which
revolves on a pin, is drawn through the riddle g, by the pliers.
The riddle is a piece of wood or metal with sloping pins, which
lean alternately opposite ways, so as to keep the wire close down
on the board, and yet to compel it to pursue a slightly zigzag, or
rather serpentine course, which is considerably magnified in the
figure.
In practice, the riddle is made wider than represented, so as to
contain about half a dozen rows of pins suitable to as many sizes
of wire ; between every set of pins, and fixed close down to the
board, is a straight wire about three times the diameter of one
to be straightened : very great importance is attached to this latter
or central wire ; being itself straight, it serves as a metallic bed for
the small wire to run upon, and it thereby gets worn into furrows
crossing it obliquely from pin to pin. The board is retained by
two staples at the far end, which fit loosely on two studs or nails
driven into the work-bench.
Figs. 276 277.
The pins are equivalent to the three forces a, b, c, of the bend-
ing-machine, page 289, several times referred to. Were the first
three pins critically placed, they would suffice to bend the wire to the
limit of its permanently elastic force, and would leave it perfectly
PllOCESSES DEPENDENT ON DUCTILITY. 325
straight; .commonly, however, five pins are used, and sometimes
seven or nine. The same riddle will not serve for wires differing
in diameter ; and were this simple tool more expensive, so as to
render it desirable, a universal riddle might be made by placing
the pins b and d, under a simple screw-adjustment; but in prac-
tice, a tap of the hammer is found sufficient to correct their posi-
tions.
It is necessary to be very particular in pulling the wire througn,
not to allow it to lean sensibly against either of the last two pins,
or it will assume a curve ; and in this manner, by drawing the wire
designedly at different angles, it may be thrown into any required
circular arc, instead of the right line.
Cylindrical shafts may be viewed as large wires, and when they
are turned with ordinary care, in a slide-lathe with a back-stay, it
becomes pretty certain that the shafts are circular, and of true diam
eters ; but they are frequently more or less crooked or bent whe.«
they leave the lathe.
In straightening the axes or shafts intended for the Calculating
Machine, which were of steel, about 6 to 10 feet long and f to 1
inch diameter, three half-round dies, Fig. 277, a, c, fixed to the bed
of a fly-press, and b, to the screw of the same, which was so adjusted
that b could only bend the portion of the shaft between a, c, to the
limit of its elasticity ; and therefore, by keeping the press con-
stantly at work, drawing the rod through, and twisting it round so
as to bend it at every point of its length, every shaft was made per-
fectly straight.
The straightening of black wrought-iron shafts previous to turn-
ing, is now accomplished by three equidistant rollers, say a foot
diameter and twelve feet long, similar to Fig. 216, p. 289. The
shaft is heated to redness, and the centre roller is raised at the mo-
ment of its introduction, and then a few turns are given to the
whole ; this straightens the shaft, and retains it so until partially
cooled ; the other end of the shaft, should it exceed the length of
the rollers, is then heated, and treated in the same manner.
All these modes are highly useful, as they operate upon the ma-
terials without partially condensing any point, from which unequal
treatment a loss of figure would be almost certain to occur, when
any such condensed point is partially removed by the turning-tool
or otherwise; as it appears to be quite impossible to prevent all
sorts of perplexities, when, by any mode of operation, the one point
of a material receives a different treatment from the remainder.
The great bulk of wire is cylindrical, but draw-plates are also
made of various other forms, as oval, half round, square, and trian-
gular, for the wires Figs. 278 ; and also of more complex forms, as
for the production of steel of the sections of Figs. 279, known as
pinion wire, the whole of the illustration being printed from the
wires themselves. The largest of 279, serves for the pinions of
clocks, and the smallest for those of watches; in these cases the
entire arbor (which carries one of the toothed wheels) is made of
326
THE PRACTICAL METAL- WORKER'S ASSISTANT.
pinion wire, but the teeth are removed from every part, excepting
that which works into the adjoining wheel of the train. The plates
for pinion wire are exactly the same as the others in principle, and
exhibit a remarkable degree of perfection in their construction, as
for every size there must be a series of many holes gradually
assuming the form of a circular foliated Gothic window, with six,
seven, eight or more foils.
Figs. 278 279
280
281.
A
A
Fig. 282.
-- rd-HT— j-
— 0 -- j_* - ^ — LJZ^ -- .J - ,
•0- *^ + *& ^ -.
Some of the printed calicoes and muslins are also curious ex-
amples of the wire-drawing process; the pattern Fig. 280, consists
of no less than 205 different pieces of copper wire of various forms,
fixed into a wood block ; the surface of the wires, when filed smooth,
are printed from after the manner of printers' types ; the few de-
tached pieces, Fig. 281, show some of the sections of such wires,
and which may be combined in endless variety. In the same
manner the specimen of music, Fig. 282, is printed from the sur-
faces of detached wires and slips of copper fixed in a wooden
block ; this is only one amongst the many ingenious processes for
printing music by letter-press or surface printing.
Figs. 283
284
285
286.
Fig. 283 represents the double-plates or swage-bits used for some
of the pieces in Figs. 280 and 282; the dies are 'fitted into a small
fram* or cramp with a side screw (much the same as dies for cut-
ting screws), so that the metal may be gradually reduced by one
PROCESSES DEPENDENT ON DUCTILITY. 827
pair of swage-bits. This method is very much employed by the
silversmith and goldsmith for mouldings, the tools being much
cheaper than rollers : the piece 284 was thus prepared for the edg-
ing of silver and gold boxes; it is bent round to the form of the
box or cover, whether square, circular or oval, and the rebate on
the straight side of the band serves for receiving the flat plate to
constitute the cover.
The most perfect example of this application of the drawing
process is in the British Mint: two fixed rollers are employed after
the manner of a draw-plate, and the long strip of gold or silver,
when rolled very nearly to the thickness, is drawn through the
stationary rollers, by dogs attached to one of the links of an endless
chain, which is in continual motion from the steam-engine. It
was found barely possible to make the surfaces of revolving rollers
so truly concentric that the equality of thickness in the metal
could be obtained with the rigorous exactness required, so as to
dispense entirely with the necessity of scraping every piece individ-
ually, a mode still practised in some of the Continental mints.
The metal, when drawn, is tested by punching out one blank at
each end ; these are carefully weighed, and if found correct, the
whole strip is punched into blanks ; and such is the accuracy of the
drawing and punching processes, that without the smallest after-
adjustment, any fifty or one hundred blanks weigh alike to the
fraction of a grain.
The window lead, shown in section in Fig. 285, does not admit
of being drawn in the ordinary manner, from the softness of the
material, nor of being rolled, because of its undercut section ; the
two principles are, therefore, curiously combined in the glazier's
vice. It may be conceived that the shade lines of 286, represent
parts of two narrow rollers with roughened edges (equal in thick-
ness to the glass), which indent the bottom of the groove, and
thereby carry the lead between the figured side-pieces, one
only shown. In some cases cutting is combined with drawing,
cutters are then fixed to the draw plate ; this method has been
adapted to making rules and similar rods ; and in perfecting the
flattened wire for the reeds used in looms, the edges are rounded by
reeling the wire beneath a forked cutter, a process intermediate
between turning and planing.
The process of wire-drawing is seldom practised by the general
mechanician, and still less by the amateur ; but when it is neces-
sary to produce a wire either of some unusual section not prepared
by the manufacturer, or that the equality of size requires more
than usual exactness, the process may be accomplished in the small
way, by fixing the draw-plate in the tail- vice and drawing the wire
through with the pliers or a hand vice, or by a reel moved by a
winch handle.
DRAWING METAL TUBES. — The perfection of tubes is mainly de-
pendent on the drawing process, conducted in a manner similar to
that employed for drawing wire. Many of the brass tubes foi
328 THE PRACTICAL METAL- WORKER^ ASSISTANT.
common purposes, when they have been bent up and soldered edge
to edge, as in Fig. 231, page 294, are only drawn through a hole
which makes them tolerably round and smooth externally, but leaves
the Interior of the tubes in the condition in which they left the
lire after they were soldered, and nearly as soft as at first.
The sliding tubes for telescopes, and many similar works, are
" drawn inside and out" and rendered very hard and elastic, by the
method represented in Fig. 287, the form of the plate b being ex-
aggerated to explain the shape. For example, the tube when sol-
dered is forced upon an accurate steel cylinder or triblet, in doing
which it is rounded tolerably to the form with a wooden mallet, so
288.
-±i4
as to touch the mandrel in places ; the end is set down with the
hammer around the shoulder or reduction of the triblet, and on the
drawing tube and triblet. by means of the loose key or transverse
piece a, through the draw-plate b, the tube becomes elongated, and con-
tracted close upon the triblet at every part, as the metal is squeezed
between the mandrel and plate. The fluted tubes for pencil-cases,
such as c, are drawn in this manner through ornamental plates,
the triblets being in general cylindrical. Some of the drawn
tube called joint- wire, is much smaller than d, and is used by
silversmiths for hinges and joints. It is drawn upon a piece of
steel wire, which being too small to admit the shoulder for holding
on the tube, the latter is tapered off with a file, and the tube and
wire are grasped together within the dogs, and drawn like a piece
of solid wire. A semicircular channel is filed half-way in both
the parts to be hinged, and short pieces of the joint- wire are sol-
dered in each alternately.
Triangular, square, and rectangular brass tubes are in common
use in France for sliding rules and measures. These are made in
draw-plates with movable dies, Fig. 288, which admit of adjust-
ment ibr size. The dies are rounded on their inner edges, and are
contained in a square frame with adjusting screws, and the whole
lies against a solid perforated plate.
In the general way, tubes of small diameters are completed at
two draughts — sometimes three are used — and by this time the
tube has received its maximum amount of hardness ; therefore the
first thickness of the metal and the diameter of the plates require
PROCESSES DEPEXDEXT OX DUCTILITY. 329
a nice adjustment. The tube, when finished, is drawn oft* the
triblet by putting the key through the opposite extremity of the
same, and drawing the triblet through a brass collar which ex-
actly fits it ; this thrusts off the tube, which will in general be
almost perfectly cylindrical and straight, except a trifling waste at
each end.
It requires a very considerable assortment of truly cylindrical
triblets to suit all works ; and when the tubes are used in pairs, or
to slide within one another, as in telescopes, it calls for a nice cor-
respondence or strict equality of size between the aperture of the
last draw-plate and the diameter of the triblet for the size next
larger ; and as these holes are continually wearing, it requires good
management to keep the succession in due order, by making new
plates for the last draught and adapting the old ones to the prior
stages. Sometimes, for an occasional purpose, the triblet is en-
larged by leaving a tube upon it and drawing the work thereupon ;
but this is not so well as the turned and ground surface of the
steel triblet.
Tubes from y^ inch internal diameter and 8 or 10 inches long,
up to those of 2 or 3 inches diameter and 4 or 5 feet long, are
drawn vertically by means of a strong chain wound on a barrel by
wheels and pinions, as in a crane. In Donkin's enormous tube-
drawing machine, which is applicable to making tubes, or rather
cylinders, for paper- making and other machinery, as large as 26 J
inches diameter and 6 J feet long, a vertical screw is used, the nut
of which is turned round by toothed wheels driven by six men at
a windlass.
All the tubes previously referred to are made of sheet-metals
turned up and soldered edge to edge, but lead and thin pipes for
water and other fluids have for a long period been cast as thick
tubes, some 20 to 30 inches long, and extended to the length of
10, 12, or 15 feet on triblets, which require to be very exactly
cylindrical or they cannot be withdrawn from the pipes.
The brass tubes for the boilers of locomotive engines are now
similarly made by casting and drawing without being soldered, and
some of these are drawn taper in their thickness.
The ductility of tin is very great. It is from the ordinary tin
tube of commerce (which is cast about 2 feet long, J inch thick,
and drawn out to about 10 feet), out of which is made the col-
lapsable vessels for artists' oils and colors. Pieces 3 inches long'
were extended to 36 inches by drawing them through ten draw-
plates, which are sometimes placed in immediate succession, the
one to commence just as the other had finished. The tube seemed
to grow under the operation, and it was thus reduced, without an-
nealing, from half an inch thick, as cast, to the 170th of an inch
thick, and it was stretched fully sixty times in length. This mode
of making the tubes of collapsable vessels, has been superseded
by another, presenting far greater ingenuity, and described here-
330
THE PRACTICAL METAL-WORKER'S ASSISTANT.
Some of the smallest tin tube of commerce, when removed from
the ten-foot triblet, is drawn through smaller plates without any
triblet being used. This reduces the diameter, with little change
of thickness, so that the half-inch tube becomes a nearly solid wire,
measuring about J inch diameter externally, which is known as
beading, and used to form the raised ledges around tables and
counters covered with pewter.
The accompanying sectional view gives the hydraulic press, and
au arrangement for manufacturing lead pipe. The principle is
claimed by Tetham, Cornell,
Fig. 289. Burr, and others. C is the
hydraulic cylinder, and R
the ram rising from it. A
cross-head is attached to the
hydraulic cylinder, and con-
nected with the upper cross-
head H by rods D D. On
the top of the ram a head-
block B is placed. A foot-
block F is attached to the
bottom of the lead cylinder
L, and the head-block, the
foot- block, and the lead cyl-
inder are secured firmly to-
gether by bolts T T. By
this arrangement the lead
"plug" or cylinder L is
moved upwards by the ram
R of the hydraulic press.
To the upper cross-head H
the hollow piston P is at-
tached by bolts S S. The
die Q, placed at the lower
end of the piston, hollow
throughout, communicates
with the aperture A in
the upper cross-head. The
movable core I, when in use,
is firmly fixed to the head-
block of the ram and ex-
tends upwards through the
centre of the lead cylinder,
and a little above it, so that
it is inserted through the die Q at the end of the hollow piston P.
The position of the core is regulated by rieans of the set-screws
V V, which move the core and set it centrally to the die. When
all the parts are thus arranged the lead cylinder is raised up to
the lower end of the piston; the end of the core passing through
the die.
SOLDERING. 331
The ram is forced upwards, carrying the cylinder X that con-
tains the plug of lead L ; this cylinder X passes over the hollow
piston P. The pipe is formed at the point of pressure Q, it then
passes through the hollow piston and out through the aperture A.
CHAPTEE XIX.
SOLDERING.
GENERAL REMARKS AND TABULAR VIEW. — Soldering is the
process of uniting the edges or surfaces of similar or dissimilar
metals and alloys by partial fusion. In general, alloys or solders
of various and greater degrees of fusibility than the metals to be
joined, are placed between them, and the solder when fused unites
the three parts into a solid mass. Less frequently the surfaces or
edges are simply melted together with an additional portion of the
same metal.
The chemical circumstances to be considered in respect to solder-
ing are, for the most part, set forth in the section on the fusibility
of alloys, pages 217 to 220, to which the reader is referred. It is
there explained that the solders must be necessarily somewhat more
fusible than the metals to be united ; and that it is of primary im-
portance that the metallic oxides and any foreign matters be
carefully removed, for which purpose the edges of the metals are
made chemically clean, or quite bright, before the application of
the solders and heat ; and as during this period their affinity for
oxygen is violent, they are covered with some flux which defends
them from the air, as with a varnish, and tends to reduce any por-
tion of oxide accidentally existing.
The solders are broadly distinguished as hard solders and soft
solders ; the former only fuse at the red heat, and are consequently
suitable alone to metals and alloys which will endure that tempera-
ture ; the soft solders melt at very low degrees of heat, and may
be used for nearly all the metals.
The attachment is in every case the stronger the more nearly
the metals and solders respectively agree in hardness and mallea-
bility. Thus, if two pieces of brass or copper, or one of each, are
brazed together, or united with spelter-solder, an alloy nearly as
tough as the brass, the work may be hammered, bent and rolled
almost as freely as the same metals when not soldered, because of
the nearly equal cohesive strength of the three parts.
Lead, tin, or pewter, united with soft solder, are also malleable
from the near agreement of these substances ; whereas when cop-
per, brass and iron are soft-soldered, a blow of the hammer, or
any accidental violence, is almost certain to break the joint asun-
332 THE PRACTICAL
der, so long as the joint is weaker than the metal generally ; and
therefore the joint is only safe when the surrounding metal, from
its thinness, is no stronger than the solder, so that the two may
yield in common to any disturbing cause.
The forms of soldered joints in the thin metals have been figured
and explained in pages 293 to 296 ; and soldered joints in thicker
works resemble the several attachments employed in construction
generally. When the spaces between the works to be joined are
wide and coarse, the fluid solder will probably fall out, simply from
the effect of gravity ; but when the crevices are fine and close, the
solder will be as it were sucked up by capillary attraction. All
soldered works should be kept under motionless restraint for a
period, as any movement of the parts during the transition of the
solder from the fluid to the solid state disturbs its crystallization
and the strict unity of the several parts.
In hard-soldering, it is frequently necessary to bind the works
together in their respective positions ; this is done with soft iron
binding-wire, which for delicate jewelry work is exceedingly fine,
and for stronger works is the twentieth or thirtieth of an inch in
diameter ; it is passed around the work in loops, the ends of which
are twisted together with the pliers.
In soft soldering, the binding wire is scarcely ever used, as from
the moderate and local application of the heat, the hands may in
general be freely used in retaining most thin works in position
during the process. Thick works are handled with pliers or tongs
whilst being soft-soldered, and they are often treated much like
glue joints, if we conceive the wood to be replaced by metal, and
the glue by solder, as the two surfaces are frequently coated or
tinned whilst separated, and then rubbed together to distribute and
exclude the greater part of the solder.
The succeeding " Tabular View of the Processes of Soldering"
may be considered as the index, which refers to the ordinary
methods of soldering most metals.
TABULAR VIEW
OF THE PROCESSES OF SOLDERING.
Note. — To avoid continual repetition, references are made to the
pages of this volume which illustrate the respective sub-
jects, and also to the lists on the opposite page, in which
some of the solders, fluxes, and modes of applying heat
are enumerated.
SOLDERING. '333
HARD-SOLDERING. 339.
Applicable to nearly all metals less fusible than the solders; the
modes of treatment are nearly similar throughout.
The hard solders most commonly used are the spelter solders, and silver
solders. The general flux is borax, marked A, on page 334 ; and the
modes of heating are the naked fire, the furnace or muffle, and the blow-
pipe marked a. b. g.
Note. — The examples commence with the solders (the least fusible
first), followed by the metals for which they are commonly
employed.
Fine Gold, laminated and cut into shreds, is used as the solder
for joining chemical vessels made of platinum.
Silver is by many considered as much the best solder for German
silver.
Copper in shreds, is sometimes similarly used for iron.
Gold solders laminated, are used for gold alloys. See 191-193
and 341.
Spelter solders granulated whilst hot, are used for iron, copper,
brass, gun-metal, German silver, etc., 184, 339-341.
Silver solders laminated, are employed for all silver works and
for common gold work, also for German silver, gilding metal, iron,
steel, brass, gun-metal, etc., when greater neatness is required than
is obtained with spelter-solder. 199 and 341.
White or button solders granulated, are employed for the white
alloys called button metals; they were introduced as cheap substi-
tutes for silver- solder. 188.
SOFT-SOLDERING. 341.
Applicable to nearly all the metals • the modes of treatment very
different.
The soft-solder mostly used, is 2 parts tin and 1 part lead; some-
times from motives of economy much more lead is employed, and 1J tin
to 1 lead is the most fusible of the group unless bismuth is used. The
fluxes B to G, and the modes of heating a to i; are all used with the
soft-solders.
Note. — The examples commence with the metals to be, soldered.
Thus in the list Zinc, 8, C, /, implies, that zinc is soldered
with No. 8 alloy, by the aid of the muriate or chloride of
zinc, and the copper bit. Lead, 4 to 8, F, d, e, implies
that lead is soldered with alloys varying from No. 4 to 8,
and that it is fluxed with tallow, the heat being applied
by pouring on melted solder, and the subsequent use of
the heated iron not tinned ; but in general one only of the
modes of heating is selected; according to circumstances.
334
THE PRACTICAL METAL-WORKERS ASSISTANT.
Iron, cast-iron and steel, 8, B, D, if thick heated by a, b, or c,
and also by q. 344.
Tinned iron, 8, C, D,/. 342-3.
Silver and Gold are soldered with pure tin or else with 8, E, a,
g, or h.
Copper and many of its alloys, namely, brass, gilding metal, gun-
metal, etc., 8, B, C, D; when thick heated by a, b, c, e, or g, and
when thin by/ or g. 343-5.
Speculum metal, 8, B, C, D, the heat should be most cautiously
applied, the sand-bath is perhaps the best mode.
Zinc, 8, C,/. 344.
Lead and lead pipes, or ordinary plumbers' work, 4 to 8, F, d,
or e, 342.
Lead and tin pipes, 8, D & G mixed, g} and also /. 345.
Brittannia metal, 8, C, D, g.
Pewters, the solders must vary in fusibility according to the fusi-
bility of the metal ; generally G and * are used, sometimes also G
and g, or/. 345-6.
Tinning the metals, and washing them with lead, zinc, etc.
346-.T
SOLDERING PER SE, OR BURNING TOGETHER. 347.
Applicable to some few of the metals only, and which in general
require no flux.
Iron and brass, etc., are sometimes burned, or united by partial
fusion, by pouring very hot metal over or around them, d. 347-9
Lead is united without solder, by pouring on red-hot lead, and
employing a red-hot iron, d, e, 347, and also by the autogenous
process, page 350.
"1
ALLOYS AND THEIR MKLTINO HEATS.*
FLUXES.
No. 1. 1 Tin, 25 Lead 558 Fahr.
A. Borax. 339.
2. 1 —10 — 641 —
B. Sal-ammoniac, or mur. of ammo'a. 343-4.
3. 1 — 5 — 511 —
4, 1 _ 3 __ 482 —
C. Muriate, or chloride of zinc. 344..
5. 1 _ 2 — 441 —
D. Common resin.
6. 1 — 1 — 370 —
E. Venice turpentine.
7. 1J — 1 — 334 —
F. Tallow. 342.
8. 2 — 1 — 340 —
9. 3 — 1 — 356 —
G. Gallipoli oil, a common sweet oil. 346.
10. 4 — 1 — 365 —
H. 5 — I _ 378 —
MODES OF APPLYING HEAT.
12. 6 — 1 — 381
13. 4 Lead, 4 Tin, 1 Bismuth 320 —
«. Naked fire. 336-6.
14. 3 -f- 3 — 1 — 310 —
b. Hollow furnace or muffle. 335.
15. 2 — 2 — 1 — 292 —
c. Immersion in melted solder. 344.
17.' 2 — 1 —2 — 236 —
d. Melted solder or metal poured on. 341-7.
18. 3 — 5 — 2 — 202 —
e. Heated iron not tinned. 342.
Note.— By the addition of 3 parts of mer-
cury to No. 18 it melta at 122° F.,
and may be used for anatomical
f. Heated copper tool, tinned. 342-9.
g. Blowpipe flame 336 to 339, 341, 345, 350.
A. Flame alone, generally alcohol.
injections, and for stopping teeth.
i. Stream of heated air. 346.
* The table by H. GADI.THIBR DB CLAUBRY, from which the present extract is
SOLDERING. 335
THE MODES OF APPLYING HEAT IN SOLDERING. — The modes
of heating works for soldering are extremely varied, and depend
jointly upon the magnitude of the objects, the general or local
manner in which they are to be soldered, and the fusibility of the
solders. It appears to be now desirable to advert to such of the
modes of applying heat enumerated in the tabular view, as are of
more general application, leaving the modes specifically employed
in heating works to their respective sections.
In hard-soldered works, the fires bear a general resemblance to
those employed in forging iron and steel, and already described ;
in fact, the blacksmith's forge is frequently used for brazing,
although the process is injurious to the fuel as regards its ordinary
use. Coppersmiths, silversmiths, and others, use a similar hearth,
but which stands farther away from the upright wall, so as to
allow of the central parts of large objects being soldered; the
blows are always worked by the foot, either by a treadle, as in
Fig. 42, p. 93, or more commonly by a chain from the rocking-
staff terminating in a stirrup.
Some parts of the remarks on forging iron and steel, p. 86 to
94, and also of those on hardening and tempering steel, 147 and
152, refer to similar applications of heat to those required in sol-
dering.
The brazier's hearth for large and long works, is a flat plate of
iron, about four feet by three, which stands in the middle of the
shop upon four legs : the surface of the plate serves for the support
of long tubes and works over the central aperture in the plate
which contains the fuel, and measures about two feet by one, and
five or six inches deep. The revolving fan is commonly used for
the blast, and the tuyere irons, which have larger apertures than
usual, are fitted loosely into grooves at the- ends, to admit of eas^
renewal, as they are destroyed rather quickly. The fire is some-
times used of the full length of the hearth, but is more generally
contracted by a loose iron plate ; occasionally two separate fires
are made, or the two-blast pipes are used upon one. The hood is
suspended from the ceiling, with counterpoise weights, so as to be
raised or depressed according to the magnitude of the works ; and
it has large sliding tubes for conducting the smoke to the chimney.
Furnaces are occasionally used in soldering, or the common fire
is temporarily converted into the condition of a furnace from being
built hollow, or by the insertion of iron tubes or muffles, amidst
the ignited fuel, as already explained in reference to forging and
hardening. For want of any of these means, the amateur may
use the ordinary grate, or it is better to employ a brazier or chaf-
derived, enumerates 102 different alloys intended to be used for the safety
plugs of steam boilers, in order that the fusion of the plug, and the conse-
quent escape of the water, may occur when the steam exceeds any predeter-
mined pressure, dependent on thermometric temperature. See Le Diction-
naire de I' Industrie Manufacturiere, Commercials, et Ayricole, par A. Baudrimont,
Dlauqui atne et autres. Paris, 1833. Vol. I., p. 320.
336
ing dish containing charcoal, and urged with hand-bellows blown
by an assistant, as then both hands are at liberty to manage the
work and fuel.
Fresh coals are highly improper for soldering, on account of the
sulphur they always contain ; the best fuel is charcoal, but in gen-
eral coke or cinders are used. Lead is equally as prejudicial to
the fire in soldering, as it is in welding iron and steel, or in forg-
ing gold, silver, or copper ; as the lead readily oxidizes and at-
taches itself to the metals that are being soldered or welded, pre-
venting the union of the parts, and in almost all cases rendering
the metajs brittle and unserviceable.
There are many purposes in the arts which require the applica-
tion of heat, having the intensity of the forge fire or of the
furnace, but with the power of observation, guidance, and defini-
tion of the artist's pencil. These conditions are most efficiently
obtained by the blowpipe, an instrument by which a stream of air
is driven forcibly through a flame, so as to direct it either as a
well-defined cone, or as a broad jet of flame, against the object to
be heated, which is in many cases supported upon charcoal, by
way of concentrating the heat.
The blowpipe is largely used — namely, in soldering, in harden-
ing and tempering small tools, in glass-blowing for philosophical
instruments and toys, in glass-pinching with metal moulds made
like pliers, in enameling, and by the chemist and mineralogist, as
an important means of analysis ; the instrument has consequently
received very great attention both from artisans and distinguished
philosophers.
Most of the blowpipes are supplied with common air, and gen
erally by the respiratory organs of the operator ; sometimes by
bellows moved with the foot, by vessels in which the air is con-
densed by a syringe, or by pneumatic apparatus with water pres-
sure. In some few cases oxygen or hydrogen, or the same gases
when mixed are employed ; they are little used in the arts.
The ordinary blowpipe is a light conical brass tube, about 10 or
12 inches long, from one-half to one-fourth of an inch diameter at
the end for the mouth, and from one-sixteenth to one-fiftieth at the
aperture or jet ; the end is bent as a quadrant, that the flame may
be immediately under observation.
Fig. 290 represents the same instrument when fitted with a ball
for collecting the condensed vapor from the lungs ; it is seen by
the enlarged section, Fig. 291, that the tube is discontinuous, and
any moisture within it, proceeding in the direction of the arrow, is
arrested in the ball. There are several other blowpipes for the
mouth, with various contrivances, such as a series of apertures of
different diameters, joints for portability, and for placing the jet at
different angles, and projecting parts to support the instrument
upon the table ; but none of these are in common use.
The lungs may be used for the blowpipe with much more effect
than might be expected, and with a little practice a constant stream
SOLDERING.
337
may be maintained for many minutes, if the cheeks are kept fully
distended with wind, so that their elasticity alone shall serve to
impel a part of the air, whilst the ordinary breathing is carried on
through the nostrils for a fresh supply.
The most intense heat of the common blowpipe is that of the
pointed flame ; with a thick wax candle, and a blowpipe with a
small aperture placed slightly within the flame, the mineralogist
succeeds in melting small fragments of all the metals, when they
are supported upon charcoal and exposed to the extreme point of
the inner or blue cone, which is the hottest part of the flame ; that
is, fragments of all metals which do not require the oxhydrogen
blowpipe invented by Dr. Hare of Philadelphia.
Larger particles, requiring less heat, are brought somewhat
nearer to the candle, so as to receive a greater portion of the flame ;
and when a very mild degree of heat is needed, the object is re-
moved further away, sometimes, as in melting the fluxes prepara-
tory to soldering, even to the stream of hot air beyond the point of
the external yellowish flame.
The first, or the silent pointed flame, is used by the chemist and
mineralogist for reducing the metallic oxides to the metallic state,
and is called the deoxidizing flame ; the second, or the noisy brush-
like flame, is less intense, and is called the oxidizing flame.
The artizan employs in soldering a much larger flame than the
chemist, namely, that of a lamp the wick of which is from a quarter
to one inch diameter ; this must be plentifully supplied with oil ;
the blowpipe in such cases is selected with a large aperture ; it is
blown vigorously, and held a little distant from the flame, so as to
spread it in a broad stream of light, extending over a large surface
of the work, which is in most cases supported upon charcoal.
When any minute portion alone is to be heated, the pointed flame
is used with a milder blast of air and a decreased distance.
Figs. 290
292
203
Fig. 292 is an arrangement, the use of which is attended with
no fatigue to the operator. A stream of air from a pair of bellows
directs a gas flame through a trough or shoot, the third of a cylin-
drical tube placed at a small angle below the flame. Instead of a
22
oo S THE PRACTICAL METALWORKER'S ASSISTANT.
charcoal support, they employ a wooden handle, upon which is fixed
a flat disk of sheet-iron, about three or four inches diameter, covered
with a matting of waste fragments of binding wire. entangled to-
gether and beaten into a sheet, about three-eighths or half an inch
thick ; some few of the larger pieces of wire extend round the e
of the disk to attach the remainder. The work to be soldered is
placed upon the wire, which becomes partially red-hot from the
flame, and retains the heat somewhat as the charcoal, but without
the inconvenience of burning away, so that the broad level sur
is always maintained. Small cinciers are frequently placed upon
the tool, either instead of, or upon the wire.
Sometimes, as in Fig. 293, the gas pipe is surmounted by a
square hood, open at both ends, and two blast-pipes are directed
through it ; the latter arrangement is used by the makers of glass
toys and seals ; these are pinched in moulds something like bullet-
moulds ; the devices on the seals are produced by inserting in the
moulds dried casts, made in plaster of Paris.
Makers of thermometers and other philosophical instruments
generally use a table blowpipe, with a shallow oval, or rather a
kidney -shaped lamp, Fig. 294, with a loop placed lengthways upon
the short diameter for holding the cotton, which is sometimes an
inch long and half an inch wide. The wick is plentifully supplied
with tallow or hog's lard, and a furrow is made through it with a
wire to afford a free passage for the blast from the fixed nozzle, by
the size of which, and its distance from the flame, the latter is made
to assume the pointed or brush-like character. This lamp is more
cleanly, and emits less smell than those supplied with oil ; any
overflow of the tallow is caught in the outer vessel or tray, and
when cold, the fat solidifies. The forge, Fig. 42, page 93, has also
a blowpipe and lamp to enable it to be applied to the arts in a similar
manner, and a very cheap table blowpipe is described by Dr.
Michael Faraday, in his "Chemical Manipulation," page 120-169.
Many blowpipes have been invented for the employment of
oxygen and hvdrogen; the mixed gases were first used by Dr.
Hare, of Philadelphia, who has been followed in various ways by
many others. The construction and management of nearly all the
blowpipes are described in Dr. Faraday's " Chemical Manipula-
tion," 1830, pages 107 to 123. Also in "A Practical Treatise on the
Usd of the Blowpipe," by his talented countryman, Dr. Sheridan
Muspratt, now of Liverpool, but formerly of Dublin. Two subse-
quent modifications of gas blowpipes which have been in vented for
the workshop, will alone be here described, namely, the Workshop
Blowpipe, intended for soldering, hardening, and other purpos -
and the Count de Riehemont's Airo-hydrogen Blowpipe.
The general form of the " workshop blowpipe" is that of a tube
open at the one end, and supported on trunnions in a wooden
pedestal, so that it may be pointed vertically, horizontally, or at
any angle as desired. Common street gas' is supplied through
the one hollow trunnion, and it escapes through an annular open-
SOLDERING. 389
ing; whilst oxygen gas, or more usually common air, is admitted
through the other trunnion which is also hollow, and is discharged
in the centre of the hydrogen through a central conical tube; the
magnitude and intensity of the flame being determined by the rela-
tive quantities of gas and air, and by the greater or less protru-
sion of the inner cone, by which the annular space for the hydro-
gen is contracted in any required degree.
From amongst numerous other small applications of heat, a port-
able blowpipe furnace may be noticed ; it consists of a lump of
pumice-stone three or four inches diameter, scooped out like a pan
or crucible, and filled with small fragments of charcoal ; sometimes
a conical perforated cover is added : the inside may be intensely
ignited, whilst the slow conducting power of the pumice-stone
guards the hand from inconvenient heat.
EXAMPLES OF HARD SOLDERING. — It was mentioned in the
tabular view that the several works united with hard-solders receive
nearly the same treatment ; a few examples will therefore serve
to convey a general idea of hard-soldering; a process commonly
attended with some risk of partially melting the works, because
the fusing points of the metals and their respective solders often
approach very nearly together.
Several of the hard solders contain zinc, which appears to be
useful in different ways: first it increases their fusibility; in cases
where the solder cannot be seen it serves as an index to denote
the completion of the process, for when the solder is melted the
zinc volatilizes, and burns with the well-known blue flame ; and as
at this moment some of the zinc is consumed, the alloy left behind
becomes tougher, and more nearly approaches to the condition of
the metal which it is desired to unite. The zinc may be therefore con-
sidered to act as a flux, and so likewise does the arsenic occasionally
introduced into the gold and silver solders, as the arsenic is for the
most part lost, between the processes of making and using the
solders ; but this metal being of a noxious quality, it is but little
resorted to, and besides, it renders the other metals very brittle.
In every case of soldering, a general regard to cleanliness in the
manipulation is important, and for the most part the edges of the
metals are filed or scraped prior to their being soldered, as before
observed ; in those cases in which the red-heat is employed, filing
or scraping are less imperative, as any greasy or combustible mat-
ters are burned away, and the borax has the property of combin-
ing with nearly all the metallic oxides and earthy bases, thereby
cleansing the edges of the metals should that proceeding have been
previously omitted.
The works in copper, iron, brass, etc., having been prepared
for brazing (or soldering with a fusible brass), and the joints
secured in position by binding wire where needful, the granulated
spelter and pounded borax are mixed in a cup with a very little
water, and spread along the joint by a slip of sheet metal or a
small spoon.
340 THE PRACTICAL METAL-WORKER'S ASSISTANT.
The work, if sufficiently large, is now placed above the clear
fire, first at a small distance so as gradually to evaporate the mois-
ture, and likewise to drive off the water of crystallization of the
borax ; during this process the latter boils up with the appearance
of froth or snow, and if hastily heated it sometimes displaces the
solder. The heat is now increased, and when the metal becomes
faintly red, the borax fuses quietly like a glass ; shortly after, that
is at a bright red, the solder also fuses, the indication of which is
a small blue flame from the ignition of the zinc. Just at this time
some works are tapped slightly with the poker to put the whole
in vibration, and cause the solder to run through the joint to the
lower surface, but generally the solder flushes, or is absorbed in
the joint, and nearly disappears without the necessity for tapping
the work.
It is of course necessary to apply the heat as uniformly as possi-
ble, by moving the work about so as to avoid melting the object
as well as the solder; the work is withdrawn from the fire as soon
as the solder has flushed, and when the latter is set, the work may
be cooled in water without mischief.
. Tubes are generally secured by loops of binding wire twisted to-
gether with the pliers ; and those soldered upon the open fire are
almost always soldered from within, as otherwise the heat would
have to be transmitted across the tube with greater risk of melting
the work, air being a bad conductor of heat ; it is necessary to look
through the tube to watch for the melting of the solder. Long tubes
are rested upon the flat plate of the brazier's hearth, and portions
equal to the extent of the fire are soldered in succession. The com-
mon tubes for gas-works, bedsteads, and numerous other purposes,
are soldered from the outside ; but this is done in short furnaces
open at both ends and level with the floor, by which the heat is
applied more uniformly around the tubes.
Works in iron require much less precaution in point of the heat,
as there is little or no risk of fusion ; thus in soldering the spiral
wires to form the internal screw within the boxes of ordinary tail
vices, the work is coated with loam, and strips of sheet brass are
used as solder ; the fire is urged until the blue flame appears at the
end of the tube, when the fusion is complete ; the work is with-
drawn from the fire and rolled backwards and forwards on the
ground to distribute the solder equally at every part. Other com-
mon works in iron, such as locks, are in like manner covered with
loam to prevent the iron from scaling off.
Sheet iron may be soldered by filings of soft cast-iron, applied
in the usual way of soldering with borax, which has been gradually
dried in a crucible and powdered, and a solution of sal-ammoniac.
The finer works in iron and steel, those in the light-colored
metals generally, and also the works in brass which are required
to be very neatly done, are soldered with silver-solder. From the
superior fusibility of silver-solder, and from its combining so well
with the different metals without, " gnawing them or eating them
SOLDERING. 341
away" or wasting part of the edges of the joints, silver- solder is
very desirable for a great many cases ; and from the more careful
and sparing manner in which, it is used, many objects require but
little or no finishing subsequently to the soldering, so that the
more expensive solder is not only better, but likewise in reality
more economical.
The practice of silver-soldering is essentially the same as brazing.
The joint is first moistened with borax and water; the solder
(which is generally laminated and cut into little squares with the
shears) is then placed on the joint with forceps. In heating the
work additional care is given not to displace the solder ; and for
which reason some persons boil the borax, or drive off its water of
crystallization at the red heat, then pulverize it and apply it in the
dry state along with the solder ; others fuse the borax upon the
joint before putting on the solder.
Numerous small works united with the hard-solders, such as
mathematical and drawing instruments, buttons, and jewelry, are
soldered with the blowpipe ; in almost all cases the work is sup-
ported upon charcoal, and sometimes for the greater concentration
of the heat it is also covered with charcoal. The management of
the blowpipe having been explained, it is only necessary to add
that the magnitude and shape of the flame are proportioned to those
of the works.
In soldering gold and silver, the borax is rubbed with water
upon a slate to the consistence of cream, and is laid upon the work
with a camel's-hair pencil, and the solders, although generally lam-
inated, are also drawn into wire, or filed into dust ; but it will be
remembered the more minute the particles of the granulated metals,
the greater is the degree of heat required in fusing them.
In many of the jewelry works the solder is so delicately applied
that it is hot necessary to file or scrape off any portion, none being
in excess, and the borax is removed by immersing the works in
the various pickling and coloring preparations to be adverted to.
EXAMPLES OF SOFT-SOLDERING. — The plumbers' sealed-solder,
2 parts lead and 1 of tin, melts at about 440° F. ; the usual or fine
tin-solder, 2 parts tin and 1 of lead, melts at 340° ; and the bismuth-
solders at from 250° to 270°: the modes of applying the heat con-
sequently differ very much, as will be shown.
The soft-solders are prepared in different forms suited to the na-
ture of the various works ; No. 5, p. 334, the plumbers'-solder, is
cast in iron moulds into triangular ingots measuring from 1 to 6
superficial inches in the section. No. 8, the fine tin solder, is cast
in cakes about 4 by 6 inches, and J to J inch thick ; and this and
the more fusible kinds, are trailed from the ladle upon an iron plate
or flat stone, to make slight bars, ribbons, and even threads, that
the magnitude of the solder may be always proportioned to the
magnitude and circumstances of the work.
It is very essential that all soft-soldered joints should be particu-
larly clean and free from metallic oxides ; and, except where oil is
342
exclusively used as the flux, greasy matters should be avoided, as
they prevent the ready attachment of the aqueous fluxes. It is
therefore usual with all the metals, except clean tinned plate, and
clean tin alloys, to scrape the edges immediately before the process,
so far as the solder is desired to adhere.
Lead works are first smeared or soiled around the intended joints,
with a mixture of size and lamp-black, called soil, to prevent the
adhesion of the melted solder ; next the parts intended to receive
the solder are scraped quite clean with the shave-Jiook (a triangular
disk of steel riveted on a wire stem), and the clean metal is then
rubbed over with tallow. Some joints are wiped, without the em-
ployment of the soldering iron : that is, the solder is heated rather
beyond its melting point, and poured somewhat plentifully upon
the joint to heat it ; the solder is then smoothed with the cloth, or
several folds of thick bed-tick well greased, with which the
superfluous solder is finally removed.
Other lead joints are striped, or left in ridges, from the bulbous
end of the plumber's crooked soldering-iron, which is heated nearly
to redness, and not tinned ; the iron and cloth are jointly used at
the commencement, for moulding the solder and heating the joint.
In this case less solder is poured on, and a smaller quantity remains
upon the work ; and although the striped-joints are less neat in ap-
pearance, they are by many considered sounder from the solder
having been left undisturbed in the act of cooling. The vertical
joints, and those for pipes, whether finished with the cloth or iron,
require the cloth to support the fluid solder when it is poured on
the lead.
Slight works in lead, such as lattices, requiring more neatness
than ordinary plumbing, are soldered with the copper-bit or copper-
bolt represented in Figs. 297 and 298 ; they are pieces of copper
weighing from three or four ounces to as many pounds, riveted
into iron shanks and fitted with wooden handles. All the works
in tinned iron, sheet zinc, and many of those in copper and other
thin metals, are soldered with this tool, frequently misnamed a
soldering-iron, which in general suffices to convey all the heat
required to melt the more fusible solders now employed.
•
Figs. 295 297
298.
I "the coprer-bit have not been previously tinned, it is heated in
a small charcoal stove or otherwise to a dull red, and hastily filed
SOLDERING. 343
to a clean metallic surface ; it is then rubbed immediately, first
upon a lump of sal-ammoniac, and next upon a copper or tin plate,
upon which a few drops of solder have been placed ; this will com-
pletely coat the tool ; it is then wiped clean with a piece of tow,
and is ready for use.
In soldering coarse works, when their edges are brought together,
they are slightly strewed with powdered resin contained in the box,
Fig. 296, or it is spread on the work with a small spoon ; the cop-
per-bit is held in the right hand, the cake of solder in the left, and
a few drops of the ]atter are melted along the joint at short intervals.
The iron is then used to heat the edges of the metal, both to fuse
and to distribute the solder along the joint, so as to entirely fill
up the interval between the two parts ; only a short portion of the
joint, rarely exceeding six or eight inches, is done at once. Some-
times the parts are held in contact with a broad chisel-formed tool,
or a hatchet-stake, whilst the solder is melted and cooled, or a few
distant parts are first tacked together or united by a drop of solder
but mostly the hands alone suffice, without the tacking.
Two soldering tools are generally used, so that whilst the one is
in the hand, the other may be reheating in the stove ; the tempera-
ture of the bit is very important ; if it be not hot enough to raise
the edges of the metal to the melting heat of the solder, it must be
returned to the fire ; but, unless by mismanagement it is made too
hot and the coating is burned oft, the process of tinning the bit
need not be repeated, it is simply wiped on tow, on removal from
the fire. If the tool be overheated, it will make the solder un-
necessarily fluid, and entirely prevent the main purpose of the
copper-bit, which is intended to act both as a heating tool, and as a
brush, first to pick up a small quantity or drop from the cake of
solder which is fixed upright in the tray, Fig. 295, and then to
distribute it along the edge of the joint.
The tool is sometimes passed only once slowly along the work,
being guided in contact with the fold or ledge of the metal. This
supposes the operator to possess that dexterity of hand, which is
abundantly exhibited in many of the best tin wares ; in these the
line of solder is very fine and regular. The soldering-tool is then
thin and keen on the edge, and the flux, instead of being resin, is
mostly the muriate of zinc, with which the joint is moistened by
means of a small wire or a stick prior to the application of the
heated tool; sometimes the workman cools the part just finished, by
blowing upon it as the bit proceeds in its course ; and the iron, if
overheated, is cooled upon a moistened rag placed in the empty
space of the tray containing the solder.
Copper works are more commonly fluxed with powdered sal
ammoniac, and so is likewise sheet-iron, although some mix pow-
dered resin and sal-ammoniac, others moisten the edges of the work
with a saturated solution of sal-ammoniac, using a piece of cane the
end of which is split into filaments to make a stubby brush, and
they subsequently apply resin ; each method has its advocates, but
344: THE PRACTICAL METAL-WORKER'S ASSISTANT.
so long as the metals are well defended from oxidation any mode
will suffice, and in general management the processes are the same.
Zinc is more difficult to solder than the other metals, and the
joints are not generally so neatly executed ; the zinc seems to re-
move the coating of tin from the copper soldering-tool ; this prob-
ably arises from the superior affinity of copper for zinc than for
tin. The flux sometimes used for zinc is sal-ammoniac, but the
muriate of zinc, made by dissolving fragments of zinc in muriatic
acid diluted with about an equal quantity of water, is much supe-
rior ; and the muriate of zinc serves admirably likewise for all the
other metals, without such strict necessity for clean surfaces as when
the other fluxes are used.
The copper tool is only applicable to thin metals, because it re-
quires such a degree of heat as will allow it to raise the temperature
of the work to be joined, to the melting point of the solder ; and
the excess of heat thus required for stout metals, is apt, either to
burn off the coating of solder, or to cause it to be absorbed as a
process of superficial alloying. It requires some tact to keep the
heat of the tool within proper limits by means of the charcoal or
cinder fire, but with the airo-hydrogen blowpipe, explained at page
350-2, it is easy to maintain any required temperature for an
indefinite period.
Thicker pieces of metal, such as the parts of philosophical ap-
paratus, gas-fittings, and others which cannot be conveniently
managed with the copper-bit, are first prepared by filling or turn-
ing, and each piece is then separately tinned in one of the follow-
ing ways. Small pieces, immediately after being cleaned with the
file or other tool, and without being touched with the fingers, are
dipped into a ladle containing melted solder, which is covered with
a little powdered sal-ammoniac. The flux meets the work before
it is subjected to the heat, and the tinning is then readily done ;
sometimes the work is in the first instance sprinkled with resin,
or rubbed over with sal-ammoniac water ; the latter is rather a
dangerous practice, as the moisture is apt to drive the melted metal
in the face of the operator.
Thin pieces of brass or of copper alloys, if submitted to this
method, must be quickly dipped, or there is risk of their being
attacked and partly dissolved by the solder. There is some little
uncertainty as to iron, and especially as to steel, being well coated
by dipping ; sometimes a forcible jar or a hard rub will remove
most of the tin, and it is therefore safer to rub these works with a
piece of heated copper shaped like a file, immediately on their
removal from the melted solder, which makes the adhesion more
certain.
Larger pieces of metal, or those it is inconvenient to dip into the
ladle, are first moistened with sal-ammoniac water, or dusted with
the dry powder or resin, and heated on a clear fire either of char-
coal, coke, or cinders, until the strip of solder held against them
is melted and adheres ; as the lowest heat should be always used.
SOLDERING. 345
Another cleanly way of applying the heat, and which is also em-
ployed in tempering tools, varnishing, and cementing, is to make
red-hot a few inches of the end of a flat iron bar about two feet
long, to pinch it in the vice by the cold part, and to lay the work
upon that spot which is at a suitable temperature ; the work can
be thus very conveniently managed, especially as it may be like-
wise placed in a good light.
Until the two parts of the work are thoroughly tinned, they
must be well defended from the air by the flux to prevent oxida-
tion ; they are next made a trifle hotter than is required for tin-
ning, and placed in contact whilst the solder is quite fluid, and a
little additional solder is also used ; when practicable, the two sur-
faces are rubbed together to perfect the tinning and spread the
alloy evenly through the joint ; the work is then allowed to cool
under pressure applied by the hammer handle, the blunt end of a
tool, the tail-vice, or in any convenient manner. The stages of
this practice are similar to those of the carpenter, who having
brushed the glue over the two pieces of wood, rubs them together
and fixes them with the hand screws until cold, as before ad-
verted to.
Small works are sometimes united by cleaning the respective
surfaces, moistening them with sal-ammoniac water; or applying
the dry powder or resin, then placing between the pieces a slip of
tin-foil, previously cleaned with emory-paper, and pinching the
whole between a pair of heated tongs to melt the foil ; or, other
similar modifications combining heat and pressure are used.
Many workmen who are accustomed to the blowpipe, as jewel-
ers, mathematical instrument makers, and others, apply the blow-
pipe with great success in soft-soldering ; but as the methods are
in other respects similar to those given, they do not require partic-
ular notice, except that in some cases there is no choice but to tie
the works together with binding- wire as in hard-soldering ; but
the preference is always given to detached tinning and rubbing
together.
The modern gas-fitters are remarkably expert in joining tin and
lead pipes with the blowpipe ; they do not employ the method of
the plumbers and pewterers, or the -spigot and faucet joint sur-
rounded by a bulb of solder, but they cut off the ends of the pipes
with a saw", and file the surfaces to meet in butt joints, in mitres,
or in T form joints as required. In confined situations they apply
the heat from one side only with the blowpipe and rushes ; they
employ a rich tin solder, with oil and resin mixed in equal parts
as the flux ; the work looks like carpentry rather than soldering.
The pewterers employ a very peculiar modification of the blow-
pipe, which may be called the hot-air blast, and the names for which
apparatus are no less peculiar ; a, Fig. 299, being called the hod,
and b, the gentleman. The first is a common cast-iron pot with
a close cover, containing ignited charcoal ; two nozzles leading
respectively into and from it, to allow the passage of a stream of
346 THE PRACTICAL METAL-WORKERS ASSISTANT.
air, through the pipe c, from bellows worked by the foot. The pew
ter wares, many of which are circular, are placed on the gentleman,
or a revolving pedestal, which may be adjusted by the side screw to
any height: the workmen dip the
Fig. 29.1. strip of solder in a little pot of oil, and
apply it to the joint with the right
hand, whilst they slowly revolve the
work with the left. This, which is a
very controllable application of heat,
includes in its range a moderately
large extent of the pewterer's work,
and answers the purpose extremely
well : by some, the rushes and mouth
blowpipe are used for circular as well
as for other articles in pewter.
The pewters bear nearly the proportion of the alloys Nos. 8 to
12, page 334: for the less fusible containing most tin, the solder
No. 8, or 2 tin 1 lead, is used ; for the more fusible containing
most lead, the bismuth solders, 2 tin 1 lead 1 bismuth, and others
of similar low degrees of fusibility, are employed. The first
solder is called by the pewterers hard-pale, the last soft-pale, and to
suit the pewters of intermediate degrees of fusibility, the two are
mixed in variable proportions and called middling -pale ; but the
table on page 334, and especially the original from which the 18
terms there given are extracted, would enable the solders to be
definitely proportioned to their respective metals.
The flux always used by the pewterers is Gallipoli oil ; it is a
second rate olive oil, of peculiar quality, rather thick, green, and
unfit for the table ; but its selection requires judgment.
Iron, copper, and alloys of the latter metal, are frequently
coated with tin, and occasionally with lead and zinc, to present
surfaces less subject to oxidation; gilding and silvering are partly
adopted from similar motives. As regards iron, the method of
making the tinned plate is strictly a manufacturing process, which
has been slightly noticed at page 200, and that of covering iron
with zinc, so that it principally remains to describe the ordinary
method of tinning vessels and other objects of copper, brass, and
iron, after they have* been manufactured, and which is in general
thus performed.
Copper and brass vessels are first pickled with sulphuric acid,
mostly diluted with about three times its bulk of water ; they are
then scrubbed with sand and water, washed clean and dried ; they
are next sprinkled with dry sal-ammoniac in powder, and heated
slightly over the fire ; then a small quantity of melted block-tin is
thrown in, the vessel is swung and twisted about to apply the tin
on all sides, and when it has well adhered the portion in excess is
returned to the ladle, and the object is cooled 'jn water. When
cleverly performed very little tin is taken up, and the surface looks
almost as bright as silver; some objects require to be dipped into
a ladle full of tiii
SOLDERING. 347
Iron presents rather more difficulty, the affinity of .the tin being
less strong for iron than for copper ; but the treatment is in gen-
eral nearly the same. Old works require that the grease should
be removed with concentrated muriatic acid, before the other pro-
cesses are commenced ; and in cast-iron vessels the grease often
penetrates so deeply, owing to the porous nature of the metal, that
the re-tinning is sometimes scarcely possible, and it is often more
economical to obtain a new vessel.
An alloy of nickel, iron, and tin, has been introduced as an
improvement in tinning the metals. The nickel and tin compound
is harder than tin, and endures a much longer time : it is less fusi-
ble, and will not run or melt at a heat that would cause the ordi-
nary tinning of pans to forsake the sides and lie in a mass at the
bottom. Also that as an experiment to show the tenacity of the
nickel, a piece of cast-iron tinned with the compound, had been
subjected for a few minutes to the white heat under a blast, &nd
although the tin was consumed, the nickel remained as a perma-
nent coating upon the iron.
The proportions of nickel and iron mixed with the tin in order
to produce the best tinning, are ten ounces of the best nickel, and
seven ounces of sheet-iron, to ten pounds of tin. These metals are
mixed in a crucible, and, to prevent the oxidation of the tin by
the high temperature necessary for the fusion of the nickel, the
metals are covered with one ounce of borax and three ounces of
pounded glass. The fusion is completed in about half an hour,
when the composition is run off through a hole made in the flux.
In tinning metals with this composition the workman proceeds in
the ordinary -manner. The process was discovered by M. Budie,
of the firm of Blaise and Co., Paris.
There is also another method, that of cold-tinning, by aid of the
amalgam of mercury, described at page 217; but this process
when applied to utensils employed for preparing or receiving food,
appears questionable both as regards effectiveness, and wholesome-
ness, and the activity of the muriatic acid must not be forgotten ;
it should be therefore washed carefully off with water. The tin
adheres, however, sufficiently well to allow other pieces of metal
to be afterwards attached by the ordinary copper soldering-bit.
SOLDERING PER SB, OR BURNING TOGETHER. — This principally
differs from ordinary soldering, in the circumstances that the unit-
ing or intermediate metal is the same as those to be joined, and
that in general no fluxes are employed.
The method of burning together, although it only admits of
limited application, is in many cases of great importance, as when
successfully performed the works assume the condition of greatest
strength, from all parts being alike. There is no dissimilarity be-
tween the several parts as when ordinary solders are used, which
are open to an objection, that the solders expand and contract by
heat either more or less than the metals to which they are attached.
There is another objection of far greater moment; the solders
848 THE PRACTICAL METAL-WORKER^ ASSISTANT.
oxidize either more or less freely than the metals, and upon which
circumstances hinge some galvanic or electrical phenomena ; and
thence the soldered joints constitute galvanic circuits, which in
some cases cause the more oxidizable of the two metals to waste
with the greater rapidity, especially when heat, moisture, or acids
are present.
In chemical works this is a most serious inconvenience, and
therefore, leaden vessels and chambers for sulphuric acid must not
be soldered with tin-solder, the tin being so much more freely dis-
solved than the lead. Such works were formerly burned together
by pouring red-hot lead on the joint, and fusing the parts into one
mass, by means of a red-hot soldering-iron, as noticed at page 294 ;
this is troublesome and tedious, and it is now replaced by the auto-
genous soldering, to be explained.
Pewter is sometimes burned together at the external angles of
works, simply that no difference of color may exist ; the one edge
is allowed to stand a little above the other, as in Fig. 213, page
292, a strip of the same pewter is laid in the angle, and the whole
are melted together, with a large copper-bit, Fig. 297, page 342,
heated almost to redness ; the superfluous metal is then filed off,
leaving a well-defined angle without any visible joint.
Brass is likewise burned together ; for instance the rims of large
mural circles for observatories, that are five, six or seven feet
diameter, are sometimes cast in six or more segments, and attached
by burning. The ends of the segments are filed clean, two pieces
are fixed vertically in a sand mould in their relative positions, a
shallow space is left round the joint, and the entire charge of a
crucible, say thirty or forty pounds of the melted brass a little
hotter than usual, is then poured on the joint to heat it to the
melting point. The metal overflows the shallow chamber or hole,
and runs into a pit prepared for it in the sand ; but the last quan-
tity of metal that remains solidifies with the ends of the segments,
and forms a joint almost or quite as perfect as the general sub-
stance of the metal ; the process is repeated for every joint of the
circle.
The compensation balance of the chronometer and superior
watches is an interesting example of natural soldering. The
balance is a small fly-wheel made of one piece of steel, covered
with a hoop of brass. The rim, consisting of the two metals, is
divided at the two extremities of the one diametrical arm of the
balance, so that the increase of temperature which weakens the
balance-spring contracts in a proportionate degree the diameter of
the balance, leaving the spring less resistance to overcome. This
occurs from the brass expanding much more by heat than steel,
and it therefore curls the semicircular arcs inwards, an action that
will be immediately understood if we conceive the compound bar
of brass and steel to be straight, as the heat 'would render the
brass side longer and convex, and in the balance it renders it more
curved.
SOLDERING. 349
In the compensation balance the two metals are thus united :
the disk of steel when turned and pierced with a central hole, is
fixed by a little screw-bolt and nut at the bottom of a small cruci-
ble with a central elevation, smaller than the disk ; the brass is
now melted, and the whole allowed to cool. The crucible is broken,
the excess of brass is turned off in the lathe, the arms are made
with the file as usual, the rim is tapped to receive the compensa-
tion screws or weights, and lastly the hoop is divided in two
places, at opposite ends of its diametrical arm.
A little black lead is generally introduced between the steel and
the crucible ; and other but less exact modes of combining the
metals are also employed.
Cast-iron is likewise united by burning, as will be explained by
the following example : To add a flange to an iron pipe, a sand
mould is made from a wood model of the required pipe, but the
gusset or chamfered band between the flange and tube is made
rather fuller than usual to afford a little extra base for the flange.
The mould is furnished with an ingate, entering exactly on the
horizontal parting of the mould at the end of the flange, and with
a waste head or runner proceeding upwards from the top of the
flange, and leading over the edge of the flask to a hollow or pit
sunk in the sand of the floor.
The end of the pipe is filed quite clean at the place of junction,
and a shallow nick is filed at the inner edge to assist in keying on
the flange ; lastly, the pipe is plugged with sand laid in the mould.
After the mould is closed, about six or eight times as much hot
metal as the flange requires is poured through the mould. This
heats the pipe to the temperature of the fluid iron, so that on cool-
ing the flange is attached sufficiently firm to bear the ordinary
pressure of screw-bolts, steam, etc.
Steam and water-tight joints, in cast-iron works not requiring
the power of after-separation, are often made by means of iron
cement in the following proportions : 112 Ibs. of cast-iron filings
or borings, 1 Ib. of sal-ammoniac, 1 Ib. of sulphur, and 4 Ibs. of
whitening. Small quantities of the materials are mixed together
with a little water shortly before use.
For minute cracks the cement is laid on externally as a thin
seam, or for larger spaces it is driven in with calking-irons. The
edges of the metal and the cement shortly commence one com-
mon process of rusting, and at the end of a week pr ten days the
joints will be found hard, dry, and permanent.
The method of burning is occasionally employed in most of the
metals and alloys in making small additions to old castings, and
also in repairing trifling holes and defects in new ones ; it is only
successful, however, when the pieces are filed quite clean, and
abundance of fluid metal is employed, in order to impart sufficient
heat to make a natural soldering — a process which is also, although
differently accomplished, in plating copper with silver (page 198),
as the two metals are raised to a heat just short of the melting
350
THE PRACTICAL METAL-WORKERS ASSISTANT.
point of the silver, and the metals then unite without solder by
partial alloying.
To conclude the description of soldering processes, we have to
refer to Fig. 300, which represents the airo-hydrogen blowpipe in-
Fig. 300.
vented in France by the Count de Richemont. It is in a great
measure converting the oxy-hydrogen blowpipe, invented by
Dr. Hare, to the service of the workshop, and it is done with great
simplicity and safety. The elastic tube h supplies hydrogen from
the generator, and the pipe a supplies atmospheric air from a small
pair of double bellows b, worked by the foot of the operator, and
3ompressed by a constant weight w ; the two pipes meet at the
arch, and proceed through the third pipe e to the small jet f, from
whence proceeds the flame. All the connections are by elastic
tubes, which allow perfect freedom of motion, so that the portable
blowpipe is carried to the work.
In soldering by the autogenous process, the works are first pre-
pared and scraped clean as usual, the hydrogen is ignited, and the
size of the flame is proportioned by the stop-cock h ; the air is
then admitted through a, until the flame assumes a fine pointed
character, with which the work is united after the general method
of blowpipe soldering, except that a strip of lead is used instead
of solder, and generally without any flux.
This mode is described as being suitable to most of the metals,
but its best application appears to be to plumbers' work, and it has
been adopted for such in our government dock-yards. The weight
of lead consumed in making the joints is a mere fraction of the
weight of ordinary solder, which is both more expensive and more
oxidizable, from the tin it contains. The gas soldering, as it is
called, removes likewise the risk of accidents from the plumbers'
fires, as the gas generator, which is in itself 'harmless, may be
allowed to remain on the ground whilst the workman ascends to
the roof, or elsewhere, with the pipe.
SOLDEKING.
351
Lead is interposed as solder in uniting zinc to zinc, and it is also
used in soldering the brass nozzles and cocks to the vessels of lead,
and those of copper coated with lead, used as generators. Another
Fig. 301.
very practical application of the gas flame, is for keeping the cop-
per soldering tool, Fig. 301, at one temperature, which is done by
leading the mixed gases through a tube in the handle, so that the
flame plays on the back of the copper bit. This mode seems to be
very well adapted to tin-plate and zinc works, especially as the
common street gas may be used, thereby dispensing with the neces-
sity for the gas generator, the construction and management of
which alone remain to be explained.
The gas generator, Fig. 300, when it is first charged, the stopper
1, is unscrewed, and the lower chamber is nearly filled with curly
shreds of sheet zinc, and the stopper is replaced. The cover is
now removed, and a plug with a long wire is inserted from the top
into the hole near 3 ; the upper chamber is next filled with dilute
sulphuric acid (1 acid and 6 water), until it is just seen through the
central hole to rise above the plate immediately beneath it. This
measures the quantity of liquid required to charge the vessel
without the risk of overflow. The plug is now withdrawn from
3, and the cocks 4, and h, being opened, the air escapes from the
lower vessel by the pressure of the column of water which enters
beneath the perforated bottom 5, upon which the zinc rests. The
cocks 4 and h are now closed, and by the decomposition of the
water hydrogen is generated, which occupies the upper part of the
lower chamber, and drives the dilute acid upwards, through the
aperture 3, so as to place matters in the position of the engraving,
which represents the generator about two- thirds filled with gas.
The gas issues through the pipe h, when both cocks are opened,
but it has to proceed through a safety box 6, in which the syphon
tube dips two or three inches into a little plain water introduced
at the lateral aperture 7 ; by this precaution the contents of tho
gasometer cannot be ignited, as, should the flame return through
the pipe h, it would be intercepted by the water in the safety box.
After three or four days' constant work the liquid becomes con
verted into the sulphate of zinc, and is withdrawn through the
plug 8 ; the vessel is then refilled with fresh dilute acid as already
explained, but the zinc lasts a considerable time.
The generators are made of lead, or where portability and light-
ness are required, of copper washed with lead, and all the exposed
parts of the brass work are washed and united with lead to defend
352 THE PRACTICAL METAL-WORKER's ASSISTANT.
them from the acid. Occasionally the air is likewise supplied by
aerometers, or vessels somewhat resembling the gas generator, but
which are only filled with common air, and therefore do not require
the zinc or acid.
The following is the broad difference between the airo-hydrogen
and the oxy-hydrogen blowpipes. In the oxy-hydrogen blowpipe,
the pure gases are mixed in the exact proportions of two volumes
of hydrogen to one of oxygen, which quantities when combined
constitute water, and in this particular case there is the greatest
condensation of volume, and the greatest evolution of latent as
well as of sensible heat.
The airo-hydrogen blowpipe is supplied with common air and
with pure hydrogen; this instrument is also the most effective
when the oxygen and hydrogen are mixed in the proportions of 1
to 2 ; but the nitrogen, which constitutes four-fifths of our atmos-
phere, is now in the way and detracts from the intensity of the
effect.
CHAPTEK XX
SHEARS.
«
CUTTING NIPPERS FOR WIRES. — Shears are instruments of a
character quite different from any of those hitherto described, as
the cutting edges of shearing tools are always used in pairs, and
on opposite sides of the material to be sheared or severed. In
many cases the shears are constructed after the manner of pincers
and pliers, or as two double-ended levers united at the fulcrum by
a pin, but other modes of uniting the two cutting parts of the in-
struments are also employed, as will be shown.
The sections of some varieties of thi3
Fig- 302. instrument are represented by a b c of
the annexed Fig. 302, from which it will
be seen that the edges of shears and
scissors meet in lateral contact, and pass
close against one another, severing the
material by two cuts or indentations, or
thrusts, which take place in the same
plane as that in which the blades are
situated and are moved.
Some of the largest shearing tools of the kinds used by en-
gineers, such as c, serve to divide bars of iron, 4, 5 or 6 inches
wide, and 1 to 2 inches thick, then requiring the greatest possible
solidity and freedom from elasticity.
On the other hand, some of the finest scissors of the section a,
Huch as are used by ladies In cutting lace, will cut witli the greatest
SHEARS. 353
cleanness and perfection the most flexible thread or tissue of
threads, or the finest membranes met with in animal or vegetable
structures.
But this latter kind of shears, unlike the engineer's shears, is
altogether useless unless possessed of a considerable share of elas-
ticity, to keep their edges in accurate contact at that point in which
the blades at the moment cross each other, as will be explained,
otherwise such thin materials are folded down between the blades
instead of being fairly cut. The transition from the elastic to the
inelastic kinds of shears is not, as may be supposed, by one
denned step, but by gradual stages, making it as difficult in this,
as in other classifications, to adopt any precise line of demar-
cation.
In addition to the above, or to shears properly so considered,
there are a few tools known as cutting pliers, or nippers, in which
the blades meet in direct opposition, but do not pass each other as
in the legitimate kind of shears. This kind is represented by the
section d, Fig. 302.
Cutting pliers, if they admit of being classed with shears, are
certainly the most simple of the group, and are used for cutting
asunder small wires, nails, and a few other substances. Their
edges are simply opposed wedges, exactly as shown in the above
diagram at d] and as respects the remainder of the instruments
by which their wedges are composed, the most simple kind ex-
actly resembles carpenters' ordinary pincers for drawing out nails,
except that the cutting pincers are made with thinner edges ; and
Figs. 303 to 306 represent different kinds of cutting pliers and
nippers.
When cutting nippers are compressed upon a nail or a piece of
wire, they first indent it on opposite sides, and when from their
penetration the surfaces of the wedges exert a lateral pressure
against the material, the latter eventually yields, and is torn asun-
der at the moment the pressure exerted by the wedges exceeds the
cohesive strength of the central metal yet uncut. Consequently
the divided wire shows two beveled surfaces, terminating in a
ridge slightly torn and ragged. The quantity of the material
thus torn instead of being cut, will be the less, the softer the metal
and the keener the pliers ; but experience shows an angle of
about 30 to 40 degrees to be the most economical for the edges of
such tools.
Little remains to be said on the varieties of cutting pliers; most
of these used by general artisans and clockmakers are smaller than
carpenters' pincers, and the extremities of the jaws are beveled as
in watch-nippers, Fig. 303, that they may cut pins lying upon a flat
surface. Other cutting pliers, called side-nippers, are oblique, as in
Fig. 304. Those used for the dressing-case, and known as nail-
nippers, are concave on the edge, to pare the nails convex ; and
another kind, known as nipper-pliers, bell-hangers1 or lottkrs1 pliers,
have flat points at the end for grasping and twisting wires, and
23
354 THE PRACTICAL METAL-WORKER'S ASSISTANT.
cutters on the sides for removing the waste ends, as shown in
Fig. 305.
The edges of cutting nippers are apt to be notched if used upon
wires, or if wriggled whilst the cutting edges are buried in
Figs. 303
305 306.
the wire, and they scarcely admit of being reground or repaired.
This inconvenience led to a modification of the instrument, Fig.
306, by the enlargement of the extremities, to admit of loose cut-
ters fitted in shallow grooves being affixed by one screw in each
as shown detached at c, so that the cutters may admit of removal
and restoration by grinding, which end is effectually obtained,
although somewhat to the prejudice of the instrument, by increas-
ing its bulk.
SCISSORS AND SHEARS FOR SOFT FLEXIBLE MATERIALS. — The
nippers have edges of about 30 to 40 degrees, meeting in direct
opposition, but yet leave ragged edges on the work ; whereas the
shears have edges commonly of 90 degrees, seldom less than 60
degrees. These edges pass each other and leave the work re-
markably keen and exact.
Let the edges of scissors be ever so well sharpened, they act
very imperfectly, if at all, unless the blades are in close contact at
the time of passing ; and this imperfection is the more sensible
the thinner and more flexible the material to be cut, as it will then
fold down between the blades if they do not come in contact.
Whereas, when the blades exactly meet, the one serves to support
the material whilst the other severs it ; or rather this action is
reciprocal, and each blade supports the material for the other, ren-
'dering the office of a counter-support, or of the bench, stool or
cutting-board, used by the carpenter with the paring chisel.
On a cursory inspection of a pair of ordinary scissors, it may
be supposed that their blades are made quite flat on their faces, or
with truly plane surfaces, like the diagram Fig. 307, representing
the imaginary longitudinal section of the instrument, the two
blades of which are united by a screw, consisting of three parts
differing in diameter, namely, the head, the neck, and the thread;
the bottom of the countersink that receives the head of the screw
is called the shelf or the twitter-bit. If, however, the insides of
scissors were made flat, and as carefully as possible, they could
scarcely be made to cut slender fibrous materials, or if at all, then
SHEARS.
355
for only a short period, and additional friction would accrue from
the rubbing of their surfaces.
The form which is really adopted, more resembles the exag-
gerated diagram Fig. 308 ; the blades are each sloped some 2 or 3
degrees from the plane in which they move, so that their edges
alone come into contact ; instead of the blades being straight in
their length they are a little curved so as to overlap ; and close
behind the screw-pin by which they are united, there is a little
triangular elevation, insignificant in size but most important in
effect, which may be considered as a miniature hillock or ridge,
sloping away to the general surface near the hole for the screw.
This enlargement or bulge is technically called the "riding part,"
and, as there is one on each blade, when the scissors are opened or
that the blades are at right angles, the points or extremities only
of the riding parts come into contact, and the joints may then
have lateral shake without any prejudice. But as the blades are
closed, first the bases or points of the riding parts, and lastly the
summits or tops, rub against each other, and tilt the blades beyond
the central line of the instrument ; the effect of which is to keep
the successive portions of the two edges in contact throughout the
length of the cut, as by the time the scissors are closed, the points
of the blades are each sprung back to the central line of the scis-
sors, which is dotted in the diagram.
Although scissors when in perfect condition for work may be
loose, or shake on the joint when fully opened (and thereby placed
beyond their range of action), they will be always found to be
309.
tight and free from shake, as soon as the blades can begin to cut
the material near the joint, and so to continue tight until they
meet at the points. That all scissors do exhibit this construction
may be easily seen, as when they are closed and held edgeways
between the eye and the light, they will be found only to touch at
the points and at the riding parts, or those just behind the joint
screw, the. remainder being more or less open and gently curved ;
and their elastic action will also be experienced by the touch, as
whilst good scissors are being closed, there is a smoothness of
contact which seems to give evidence of some measure of elas-
ticity.
Fig. 309 represents the section of the one blade of a pair of
scissors, in which the elastic principle is differently introduced.
These scissors are made without the riding part, but instead thereof,
immediately behind the screw which unites the blade as usual, the
356 THE PRACTICAL METAL-WORKERS ASSISTANT.
one blade is perforated, for the purpose of admitting freely a small
pin or stud fixed to the end of a short and powerful spring, so that
the stud s, from acting on the opposite blade, throws the points of
both towards each other, so as to give them a tendency to cross,
but which being resisted by the edges of the blades touching one
another, keeps them very agreeably in contact throughout their
motion, and causes them to cut very well.
If further evidence is wanted of the elastic principle in scissors,
it is distinctly shown in sheep shears, which besides their ostensi-
ble purpose of shearing off the fleece, are used by leather dressers
and others. It is well known that sheep shears, Fig. 315, page
361, are made as one piece of steel, which is tapered at each end
to constitute the cutting edges, is then for a distance fluted and
straight to form the semi-cylindrical parts for the grasp, and that in
the centre or opposite extremity, the steel is flattened and formed into
a bow by which the blades are united and kept distended ; sheep
shears consequently require no joint pin, and the hands have only
to compress them, as they spring open for themselves. If sheep
shears are examined when fully opened, or when partially closed
by tying round the blades a loop of string, it will be found that
the blades have a tendency to spring into contact, as after having
been pressed sideways and asunder, the cutting edges immediately
return into exact contact the moment the distending pressure is
removed.
The construction of scissors with the riding-place, as adverted
to in Fig. 308, is that which ordinarily obtains in most scissors,
from the finest of those used by ladies, to the heavy ponderous
shears for tailors, which sometimes weigh above six pounds, and
are rested on the cutting-board by one of their bows, that are
large enough to admit the whole of the fingers.
The peculiar form of the insides of the blades is in all cases of
paramount importance, and in the manufacture of fine scissors is
attended by a person called a "putter-together" whose province it
is to examine the screw-joint, and see to the form of the riding-
places^ and lastly to set the edges of the scissors, which for gen-
eral purposes are sharpened on an oilstone at an angle of about 40
degrees, but for the fine scissors more nearly upright or at 30
degrees from the perpendicular.
So important, indeed, is the configuration of the inner face of
scissors, that they should never be ground or meddled with at that
part, but by a person fully experienced in their action, and scissors
may with careful usage be kept in order for years without being
ground, if the edges are occasionally set on the oilstone at the in-
clination above referred to. It will frequently happen that well-
made scissors which appear to grate a little when closed, merely
do so from dirt or dust, which if removed by passing the finger
along the edges, will restore the scissors to their smooth and
pleasant action.
It seems quite uncalled for to enter into the separate description
SHEARS. 357
of various instruments known as button-hole scissors, cutting-out,
drapers', flower, garden, and grape scissors, horse trimming scis-
sors ; hair, lace, lamp, nail, paper, pocket, stationers', and tailors'
scissors, and many others ; nor of the large shears for the garden^
such as pruning, trimming, and border shears, the distinctions be-
tween which varieties are sufficiently known to those who use the
several kinds, but the author will merely notice such of them as
present any peculiarity of structure.
Button-hole scissors are notched out towards the joint screw as
in Fig. 311, so as to enable the instrument to make the incision a
311.
Fig. 312.
little distant from the edge of the material ; the joint must be made
stiff, so as to prevent the points catching against each other.
Flower and grape scissors assume the section of Fig. 310, so that
they first cut the stem, and then hold it like a pair of pliers ; the
one blade requires to be made in two parts riveted together ; when
entirely closed they present an elliptical section a ; and b shows
how the stem of the flower is grasped; the blades are rounded at
all parts that they may not injure the plants.
Lamp scissors have the one blade very broad, and with a little
rim, to prevent the snuff of the lamp falling on the carpet.
Nail scissors for the dressing-case are made very strong, and
with short blades. In using scissors formed in the ordinary mode,
the fingers and 'thumb of the right hand have naturally a tendency
to press the blades together, in that position in which they are in-
tended to cut ; but the left hand, on the contrary, has a tendency
to separate the blades and defeat the principle on which scissors
act. Therefore nail scissors are made in pairs, and formed in
opposite ways, or as *' rights and lefts," so that they may suit the
respective hands.
Pocket scissors have blades which admit of being locked to
gether in the form represented in Fig. 312, as the point of one blade
catches into a small spring near the bow of the other ; and the in-
strument cannot be opened until the spring or catch is released
with the nail. When closed for the pocket, the bows stand on one
line as at a b, when opened for use as at a c.
Surgical scissors are of many forms, but have generally short
blades, and long, straight, slender handles, that the hand may not
358
impede the vision. In some of the surgical scissors the blades are
curved as scimitars, and others are curved sideways ; these kinds
are difficult to make, as the elasticity of contact in the blade is re-
quired nevertheless to be maintained.
Many of the shears and scissors used in gardening, only differ
from scissors and shears in general in their size, and the adaptation
of their handles, some of which are of wood, and placed at an
angle of 40 or 50 degrees, as in the letter Y inverted. Ocher
garden shears used in trimming borders, have handles a yard long
and inclined about 80 degrees to the blades, which may therefore
lie on the ground whilst the individual stands nearly erect. Some
of the border shears have rollers to facilitate their movement along
the ground.
In pruning shears and scissors, two peculiarities of form are
judiciously introduced. In the more simple of the two kinds,
which is shown in Fig. 313, the one part of the instrument termi-
nates in a hook, with a broad and sometimes a roughened edge, to
retain the branch from slipping away ; the other part of the in-
strument is formed as a thin cutting blade, the edge of which is
convex. Theoretically it should be part of a logarithmic spiral,
in which case the edge of the cutter would present a constant angle
to the work throughout its action, and slide laterally through the
incision made by itself, or make a sliding cut ; whereas if the edge
of the blade were radial, it would make a direct cut without any
sliding, as in a paring chisel. The spiral blade cuts more easily,
and will therefore remove a larger branch, with an action precisely
analogous to that of the oblique cutters in some of the planes,
although differently produced.
Some of these instruments, when a little modified in form, are
mounted on poles from 6 to 10 feet long, and are actuated by a
catgut; this tool, which is known as the Avemncator, is very
efficient for pruning at a considerable distance above the head.
The other pruning shears represented in Fig. 314, are denom-
Pigs. 313 6 a 314.
inated sliding shears ; the pin that unites the two parts fits in a
round hole in the one blade and a long mortise in the other, and a
link or bridle-rod c e, is attached by a screw to each lever ; in con-
sequence, when the instrument is fully opened the pin or fulcrum
is at the end a, of the mortise, whereas, on tne shears being grad-
ually closed, the cutting blade slides downwards upon the pin until
the fulcrum is near the opposite end b. In this modification of
SHEARS. 359
shears the sliding action is produced to a much greater extent
than with the spiral blade, but the construction is a little more ex-
pensive ; and as the instrument is not provided with bows for the
fingers, the spring d e, is added to throw it open.
Before dismissing this subject, two modifications of shears will
be briefly adverted to ; those used b y card makers, and the revolving
shears employed in manufacturing woollen cloth.
Card paper is prepared in large sheets ; when dried and pressed
it is cut into square pieces of the required sizes by means of long
shears, the one blade of which is fixed at the end of a table, and
has the joint at the farther extremity, whilst the cutting blade has
a handle in front, and moves through a loop to keep the blade in its
position, as in some chaff-cutting machines ; there is also a stop
fixed parallel with the blades, and as distant as the width of the
slips into which the card is first divided, and these slips are then
cut again the length way of the cards. The shears are moved so
rapidly, that the action sounds like that of knocking at a door, and
still the cards agree most rigidly in size.
Revolving shears or "perpetual shears" are used for shearing off
the loose fibres from the face of woollen cloths. For narrow cloths
the cylinders are 80 inches long and 2 in diameter, eight thin knives
are -twisted around the cylinders, making 2 J turns of a coarse screw,
and are secured by screws and nuts which pass through flanges at
the ends of the axis : formerly the cylinders were grooved and fitted
with several thin narrow plates of steel 6 or 8 inches long. The
edges of the eight blades are ground so as to constitute parts of a
cylinder, by a grinder or strickle fed with emery, passed to and fro
on a slide parallel with the axis of the cylinder, which is driven at
about 1200 turns in the minute.
In use, the cylinder revolves about as quickly, and in contact
with the edge of a long thin plate of steel, called the ledger-blade,
which has a very keen rectilinear edge, measuring 40 to 50 degrees ;
the blade is fixed as a tangent to the cylinder, and the two are
mounted on a swing carriage with two handles, so as to be brought
down by the hands to a fixed stop. The edge of the ledger-blade
is sharpened, by grinding it against the cylinder itself with flour
emery and oil, by which the two are sure to agree throughout their
length.
The cloth, before it goes through the process of cutting, is
brushed so as to raise the fibres, it then passes from a roller over a
round bar, and comes in contact with the spring bed, which is a
long elastic plate of steel, fixed to the framing of the machine, and
nearly as a tangent to the cylinder ; this brings the fibres of the
cloth within the range of the cutting edges, which reduce them
.very exactly to one level. The machine has several adjustments
lor determining, with great nicety, the relative positions of the
cylinder, ledger-blade and spring bar, but which could not be con-
veyed without elaborate drawings. Formerly the cloth was passed
over a fixed bed having a nearly sharp angular ridge, but which
360 THE PRACTICAL METAL-WORKER'S ASSISTANT.
mode was far more liable to cut holes in the cloth than the spring
bed.
Broadcloths require cylinders 65 inches long, and machinery of
proportionally greater strength. In the cross-cutting machine, the
cloth is cut from list to list, or transversely, in which case the cloth
is stretched by hooks at the two edges, and there are two spring
beds ; the cylinder in this machine is 40 inches long, and the cloth
is shifted that quantity between every trip until the whole piece is
sheared. The perpetual shears are also successfully applied to
coarse fabrics, including carpets.
A modification of the above revolving shears, made in a much
less exact manner for mowing grass lawns, is fitted up somewhat
as a wheelbarrow, or hand truck, so that the rotation of the wheels
upon which the machine is rolled along, gives motion to the shears,
which crop the grass to a level surface.
SHEARS FOR METAL WORKED BY MANUAL POWER. — When
metals are very thin, such as the latten brass used for plating, and
other purposes, they may be readily cut with stout scissors ; and
accordingly, we find the weakest of the shears for metal are merely
some few removes in strength beyond the strong scissors for softer
substances.
It is however to be observed that, as common scissors are sharp-
ened to an angle varying from about 50 to 60 degrees, they may
fairly be considered to cut the materials submitted to their action ;
but shears for metal have in general rectangular edges, as they are
seldom more acute than 80 degrees, and therefore instead of cutting
into the material, they rather force the two parts asunder, by the
pressure of the two blades being exerted on opposite sides of the
line of division.
It was recently stated to be of the utmost importance, that the
blades of the weaker or elastic kind of shears should be absolutely
in contact, or else thin flexible materials would be folded down
between their blades without being cut.
And it may now be urged as of equal importance, that the blades
of the shears for metal should be also exactly in contact, not that
rigid plates or bars of metal could be bent or folded down between
their blades, even if these were a little distant ; but the resistance
to the operation of cutting would be then enormously increased,
because the force exerted to compress the shears would not be then
exerted in the line of their greatest resistance, which is strictly the
case when the edges truly meet in one plane.
If the blades were distant as in Fig. 320, from the want of direct
support, the bar or plate would be tilted up and become jammed ;
this would tend further to separate the blades, and the shears would
be strained or perhaps broken without dividing the bar, whereas
all these evils are avoided if the shears close accurately in one and
the same plane, as if the lower blade were shifted- to the dotted line,
and in which case they require the least expenditure of power and
act with the best effect.
SHEARS.
361
Hand shears, which are the smallest of these tools, are made of
the form represented in Fig. 316, and vary from about four to nine
319
Figs.
315
318
320.
inches in total length. They are much used by tinmen, copper-
smiths, silversmiths and others who work in sheet metals, and are
often called snips, to distinguish them from bench shears. Some-
times, however, they are fixed by the one limb in the table or tail
vice, and then become essentially bench shears, — and this enables
them to be used with somewhat increased power.
Bench shears of the ordinary form are represented in Fig. 317.
The square tang t is inserted in a hole in the bench, or in a large
block of wood, or else in the chaps of the bench vice itself. A
less usual modification is seen in Fig. 318, with the joint at the far
end, and the cutting part between the joint and the handle.
Bench shears vary in total length from about one foot and a half
to four feet, and the blades occupy about one-fifth of the length.
Sometimes to increase the power of these shears the handle is
forged thicker at the end to add weight, so that when the instru-
ment is closed with a jerk, it may by its momentum cut thicker
metal than could be acted upon by a simple thrust ; but when con-
siderable power is required it is better to resort to the shears next
described.
Purchase shears, which are represented in Fig. 321, are in every
respect more powerful than those previously noticed ; the framing
is much more massive, and the cutters are rectangular bars of
steel inserted in grooves, to admit of their being readily sharp-
ened or renewed. Instead of the hand being applied on the first
lever or a b, a second lever c d e is added, and united to the first
by the link b d, and but for the limit of the paper the hand lever
c d e would have been represented of twice its present length.
As the length of the part a b is three to four times the length of
c d, the hand has to move through three to four times the space it
would if applied directly to the shear lever, and consequently the
purchase shears have three to four times the force of common
shears, supposing the manual lever to be of equal length in eaoA
362
THE PRACTICAL METAL-WORKER'S ASSISTANT.
kind. There is usually at the back of the moving blade a very
powerful spring or back stay, to keep the two edges in contact, and
still further behind a stop to determine the lengths or widths of
the pieces sheared offl
Fig. 321. b
Before using the shears, in those cases where the stop is not em-
ployed to determine the width, it is usual to mark on the work the
lines upon which it is intended to be sheared. The shears are then
opened to the full, and the extremity of the line is placed in the
angle formed by the jaws. If the work is short, it is also observed
whether the opposite end of the line lies exactly on the edge of
the lower blade ; but if the work is long, the guidance is less easy.
When the blades are closed the work will probably slip endlong,
notwithstanding the resistance of the hand, until the angle at which
the blades meet is so far reduced that they begin to grasp the work,
when the extreme edge will be first cut through, and then the
incision will be extended to the full length of the blades.
As, however, each successive portion is severed, the two parts
are4 bent asunder to the angle formed by the blades, and both pieces
become somewhat curved or curled up. Provided the cut is
through the middle of the sheet, so that both are equally strong,
the two parts become curved in the same degree ; but when a nar-
row and consequently weaker piece is removed from the edge of
a wide sheet, the curling-up occurs almost exclusively in the nar-
row strip, on account of its feebleness. In long pieces it is some-
times necessary to increase the curvature, in order that as the work
is sheared oft' the one part may pass above, and the other below
the rivet or screw by which the halves of the shears are united.
When from use or accident the joint becomes loose, so as not to
retain the two parts in contact, in order to nlake the shears cut,
the moving half must be pressed against that which is fixed to the
p.'destal or tail vice. Sometimes the sway of the blades of jointed
SHEARS. 363
shears is prevented by allowing the moving arm to pass through a
loop or guide which may retain it in position.
Such a guide is mostly used in the light shears with which prin-
ters cut their space line leads, or those thin strips of metal inserted
between the lines of type, to separate them and make the printing
more open. The leads are cast in strips about a foot long, and are
cut into pieces of the exact width of a page, by laying them in a
trough having at the end a pair of shears, and beyond these a stop
to determine the precise length, so that any number of the leads
may be cut exactly to the length required. Before adverting to
the powerful shears used by engineers, two- modifications of those
already described will be noticed.
Fig. 319, page 361, represents the section through the blades of
a pair of shears, by which the tags or tin ferrules at the end of
silk laces are cut and bent at one process, the general aspect of the
tool being that of Fig. 317, page 361. The shearing blades are
shaded obliquely in Fig. 319, and to the lower, which is fluted on
the edge, is attached a stop that determines the width of the piece
removed from the strip s, to make the tag. The upper shear blade,
which is ground more acutely than usual, carries a ridge piece
(shaded vertically), which compresses the strip as it is cut off, into
the fluted edge of the lower blade, and thereby throws it into a chan-
neled form ; and by the employment of a pair of hollow pliers, or
else a light hammer and a hollow crease, the bending is readily
completed, and the tag attached to the cord.
A nearly similar machine, but constructed more in accordance
with the printers' space line shears, is used for cutting slips of thin
latten brass, into the channeled pens used in stationers' machines
for ruling the blue and red lines on paper for account books, etc.
The one side of a slip of brass 1 J inch wide, is thus cut and chan-
neled at intervals suited to every line ; the sides of every channel
are closed to form a narrow groove, and the intervening pieces are
removed with hand shears. The compound pen is fixed on a hinged
board, and a strip of thick flannel laid at the top of the pen, is
saturated with ink which flows steadily down all the channels,
whilst the paper is moved horizontally under the pens, by two or
three rollers and tapes, somewhat as in the feeding apparatus of
printing machines, and thus the whole page is ruled one way and
very quickly.
Shears of the above kinds, with rectilinear blades, are not suited
to cutting out curvilinear objects, such for example as the sides of
callipers a, Fig. 349. The outline of such callipers is first of all
marked on the sheet of steel from a templet, and with a brass wire
which leaves a sufficient trace ; the outline is followed with a ham-
mer and chisel upon an anvil, the chisel having a rounded or con-
vex edge. Detached cuts running into one another are made
round the curve, and the work is finally separated by pinching it
in the tail- vice successively at all parts of the curve, and wrig-
gling the other edge of the sheet with the hand until it breaks.
THE PRACTICAL METAL-WORKER'S ASSISTANT.
The vice is often also used for cutting off straight pieces, which
are then fixed with the line of division exactly flush with the
chaps, and an ordinary straight chisel is so applied, that the cham-
fer of the tool rests on the chaps of the vice, and the edge lies at
a small angle to the work, and after each successive blow, the
chisel is moved a little to the left without losing its general
position.
ENGINEERS' SHEARING TOOLS ; GENERALLY WORKED BY STEAM
POWER. — The earliest machines of this class were scarcely more
than a magnified copy of the bench shears shown on page 361,
but made very much stronger ; thus, Fig. 822 represents a shear-
ing and squeezing tool used in some iron works and smithies. It
has one massive piece that is fixed to the ground, and jointed to
it is the lever, which carries at a, a pair of shearing cutters situated
exactly on two radii struck from the centre of motion ; this
Figs. 322
323
325.
machine has also two squeezers b, for moulding pieces of iron
when red-hot to the particular forms of the dies. The longer end
of the lever is united by a connecting-rod to an eccentric stud in
the disk d, which is made to revolve by the steam-engine.
Shears are sometimes moved by means of an axis carrying two
rollers, placed at the extremities of a diametrical arm, as in Fig,
323. The one roller acts on the radial part of the shear lever in
the act of cutting, and the curved part then allows the lever to
descend by its own weight rapidly, yet without a jerk, by the time
the other roller comes into action for the succeeding stroke of the
machine, which by this double eccentric makes two reciprocations
for every revolution of the shaft.
It is, however, more usual to employ cams, as in Fig. 324, and
in this case the part of the cam which lifts the shear lever is usu-
ally spiral, so as to raise it with equal velocity ; the curve of the
back is immaterial, provided it forms a continuous line so as to
prevent the lever descending with a jerk.
Fig. 325 represents the double shears ; the one part, shown also
detached, presents two horizontal but discontinuous edges with
the axis in the centre, this piece is fixed to a'firm support ; the
other or the moving part somewhat resembles the letter T or a
pendulum, to the lower end of which, and beneath the floor, is
SHEARS.
365
jointed a connecting-rod, that unites the pendulum with an eccen-
tric or crank driven by the engine. The machine is double, or
cuts on either side, and has two pairs of rectangular cutters of
hardened steel, which may be shifted to bring the four edges of
all of them successively into action.
Boiler makers have great use for powerful shears for cutting
plate iron from J to J, and sometimes f inch thick ; and the next
stage of their work is to punch the rivet holes by which the plates
are attached. The two processes of shearing and punching are so
far analogous in their requirements, that it is usual to unite the
two processes in one machine ; and as it sometimes happens the
F.g. 326.
boiler maker's yard is at a distance from the general factory, it
then becomes necessary to work the shears by hand with a winch
handle, and which is effected in the manner shown in Fig. 326, by
the introduction of only one wheel and pinion. The wheel is fixed
on the cam shaft, the pinion on the same axis that carries the
heavy fly-wheel employed to give the required momentum ; this
mode of working the shearing and punching engine is perfectly
successful, but of course less economical than steam or water power,
the agency of which the machine is also adapted to receive.
When shears that move on a joint and have radial cutters as in
Fig. 322, are employed for thick bars, owing to the distance to
which their jaws are opened, they meet at a considerable angle,
and therefore from their obliquity they do not grasp the thick bar,
but allow it to slide gradually from between them, to prevent which
a rigid stop is added at the part c, Fig. 322, when, as the bar can
no longer slide away it becomes severed. The shears with radial
cutters, are also liable from1 their very oblique action to curve the
plates ; neither do they serve for making long cuts, as the joint
then prevents the free passage of long work.
these inconveniences, however, are obviated in the shearing
366
THE PRACTICAL ttETAL-WORKER's ASSISTANT.
machines with slides, in which the edges approach in a right lino
instead of radially, and are also nearly obviated in the very massive
and powerful shearing and punching tool with jointed lever, first
employed by French engineers and represented in Fig. 326, which
occupies an entire length of eleven feet, and serves for cutting plates
not exceeding } inch thick, cutting 12 inches in length at a time,
and punching holes of 1 J inch diameter in } inch iron. The shear-
ing cutters are in this machine 15 inches long and raised above the
centre of motion ; as they lie on a chord instead of a radius, the
longest pieces may therefore be cut without interference from the
joint, and the cutters have the further advantage of meeting at a
much smaller angle than if fitted radially.
The portable punching and shearing machine shown in front and
side elevation in Figs. 327 and 328, will serve for a general exam-
ple of such machines, as the differences in the several constructions
are only those of form and arrangement, and not of principle.
Figs. 327
328.
This machine stands upon a base of a triangular form, and has
in front a strong chamfer slide, which is reciprocated in a vertical
line, by an eccentric that is concealed from view, it being immedi-
ately behind the slide, and upon the same axis, as the eccentric is
the toothed wheel. The pinion that takes into this wheel, is on
the shaft that carries the fly wheel, and one of the arms of the latter
receives the handle by which the machine is usually worked ; or
if it is driven by power, fast and loose pulleys are then fixed on
the same axis as the fly wheel.
The upper part of the slide carries a shearing cutter, which is
SHEAK3. 367
nbo-Jt 7 inches wide, and meets a similar cutter that is fixed to the
•jpper and overhanging part of the casting. The cutters, although
ground with nearly rectangular edges, are beveled to the extent of
about three-fourths of an inch in the direction of their length, that
thev may commence their work on the one edge, and therefore
more gradually than if the entire width of the cutter penetrated at
the same instant : this degree of obliquity does not cause the work
to "slide from the shears, neither does it materially curl up the
work ; and as the blades are quite clear of the framing, a cut may
be extended throughout the longest works, provided the cut is not
more than five inches from the edge of the plate, the distance of
the cutters from the framing of the machine.
The above machine, which measures in total height about five
feet, makes 12 or 15 strokes per minute, shears J inch iron plates,
and punches f holes in iron J inch thick. A -larger machine
makes 10 or 12 strokes per minute, shears f inch plate, and punches
1J inch holes in iron } inch thick; and a still heavier machine,
working at 8 or 10 strokes in the minute, shears 1 inch plates, and
punches 2 inch holes in iron 1 inch thick. Some of these are pro-
vided with railways by which the work is carried to the sheais or
punches, as will be described ; and the bar-cutting machine, having
only shearing cutters at the bottom, and the eccentric at the top of
the slide, is used for cutting bars not exceeding 6f inches wide by
If thick, or bars 2 or 2J- square, but we think these dimensions
of the works performed might, if required, be greatly exceeded in
heavier machines.
There is a shearing machine for cutting wide plates of sheet iron ,
which is used in the manufacture of wrought iron ; it has two wide
cutters of steel fixed to the edges of thick plates of cast-iron ; the
lower cutter is at rest and quite horizontal, the upper cutter bar is
fitted in grooves at the end of the frame, so as to be carried up and
down vertically, by a shaft or spindle immediately above the cut-
ter and parallel with it ; this sha"ft has an eccentric at each end,
and one in the centre, and three connecting links, which attach the
cutter frame to the eccentrics, and give it a small reciprocating mo-
tion. The upper cutter is a little oblique, so as to begin to act at
the one end, and in removing the strips curls them but very little.
A vice for cutting wide pieces of boiler plate, is based on the
mode of cutting thin slips of sheet metal over the chaps of the
ordinary tail vice, as described on page 363-4. The jaws of the
machine are about six feet long, faced with steel, and powerfully
closed by two perpendicular screws and nuts, one at each end,
which also secure the machine to the ground.
The plate of iron is therefore fixed horizontally and with the
line of division level with the jaws. A strong rod chisel struck
with sledge-hammers, is applied successively along the angle
formed between the work and the vice, and after the iron has been
indented the whole length, the blows of the sledges directed on the
overhanging piece of iron complete the separation.
368
THE PRACTICAL METAL-WORKERS ASSISTANT.
Fig. 329 represents the plan, and Fig. 330 the partial vertical
section of a " hydraulic machine for cutting off copper bolts."
The circle in Fig. 329 represents the cylinder of a hydrostatic
press, which is flattened to the width of the rectangular bar that is
fixed alongside of the cylinder, the two being enveloped in the ex-
ternal casting which is shaded in the section Fig. 330, and resem-
bles a stunted pillar three or four feet high. The whole of the
parts are traversed by nine sets of holes suitable to bars from f
to 2J inches diameter; the holes where they meet on the lines b b,
are furnished with annular steel cutters, and are enlarged outwards
each way to admit the work more easily.
The rod r r, to be sheared, is introduced whilst the holes are
directly opposite or continuous, and the men then pump in the in-
jection water through the pipe w\ it acts upon the annulus or
shoulder intermediate between the two diameters of the cylinder.
Figs. 329
332
333.
causes the descent of the latter with a pressure of about 100 tons,
and forces the bar asunder very quietly, and, from the annular
form of the cutters, without bruising it. When the bar has been
cut off, the injection water is allowed to flow out from beneath the
cylinder, and the latter is raised by a loaded lever beneath the
floor ready for the next stroke. The machine is far more econo-
mical in its action than the old mode of cutting off the copper
bolts with a frame saw used by hand, and the storekeeper in
charge of the bolts can, if needful, perform the entire operation
unassistedly, although usually four men work the pair of one inch
injection pumps by a double-ended lever, as in a fire engine.
In concluding this subject it is proposed to speak of the rotary
shears for metal, which have continuous action like rollers, and are
pretty generally used. In the best form of the instrument, two
spindles, connected together by toothed wheels of equal size, have
each two thin disks of different diameters, which are opposed to
each other, that is, a large and a small in the same plane, as in the
diagram, Fig. 331 ; the larger disks overlap each other and travel
in lateral contact, and therefore act just like-shears, and the two
disks in each plane meet, or rather nearly meet, so as just to grasp
between them, after the manner of flatting the rollers, the two
SHEARS.
369
parts of the strip of metal which have been severed, and by carry-
ing these forward they continually lead the yet undivided part of
the metal to the edges of the larger disks, which in this manner
quickly separate the entire strip of metal into two parts.
The machine requires that the spindle carrying the disks should
have an adjustment for lateral distance, as in flatting rollers, to
adapt their degree of separation to the thickness of the metal to
be sheared. One of the spindles should also have an endlong
adjustment to bring the disks into exact lateral contact, and the
machine requires in addition a fence or guide fixed alongside the
revolving shears to determine the width of the strips cut off.
Sometimes the two smaller disks are omitted, and the larger alone
used, as in Fig. 332 ; the circular shears are then somewhat less
exact in their action, but perform nevertheless sufficiently well for
most purposes.
Circular or rotary shears are very useful for shearing plates not
exceeding one-eighth of an inch thick, and one of the advantages
which the rotary possesses over the common shears, is the facility
with which curved lines may be followed, on account of the small
portion of the disks that are in contact, whereas the length of rec-
tilinear shear blades prevents their ready application to curves. Of
course the speed at which the machines may be driven depends on
the nature of the work, and if the cuts are straight and the plates
light, the velocity of the shears may be considerable.
The circular shears, or splitting rolls used in the works where
wrought-iron is manufactured, are composed of steel disks of eqaal
thickness, but of two diameters, arranged alternately upon two
spindles, as in Fig. 333, so as at one action to split thin plates of
iron of about 6 inches in width into very narrow pieces known as
nail rods, and into strips from half to one
inch wide, designated as bundle or split iron.
Of course different pairs of rolls are required
for every different width of the-strips thus
manufactured.
The anti-friction cam press, invented by
David Dick, of Meadville, Pennsylvania, is
destined to become o'f great use to the metal-
worker. This press is much more easily con-
structed, and can be supplied for much less
cost than that of Timothy Brahmah ; it also
can be made to accomplish its work with
much greater expedition.
There are many arrangements for shears,
punches, and presses for iron and steel, one
of which may be described thus :
A A, Fig. 334, are two eccentric wheels,
and B is a roller between. C C are two
pair of sectors, constituting the bearings
of the axes of the sectors. The axes of the sectors are of the
24
Fig. 334.
370
THE PRACTICAL METAL-WORKER'S ASSISTANT.
knife-edge shape. D is the bearing, and R is the follower of the
sectors.
This combination, Fig. 334, is inclosed in a frame, Fig. 335.
The centre roller B is made to revolve, which carries by its trac-
tion the two eccentric wheels A A, which have their bearings on
the faces of the sectors, which are transferred the length of their
faces right and left, the sectors being knife-edge shaped at the cen-
tres of motion 0 O, which revolve with very little friction. When
A A have made their revolution the follower R will have moved
the sum of the two eccentrics.
Figs. 335
336.
Fig. 336 is a side view with^one side of the frame removed.
A press constructed in this way, the follower moving down a
spring S, may be used to return the moving parts when the press
is relaxed.
CHAPTER XXI.
PUNCHES.
PUNCHES USED WITHOUT GUIDES. — This title may, at the first
glance, only appear to possess a very scanty relation to the tools
used in mechanical manipulation, as the ostensible purpose of a
punch may be considered to be only that of making a round or
square hole in any thin substance. But it frequently happens that
the small piece or disk so removed by the punch, is the particular
PUNCHES. 371
object sough4, and some of the very numerous objects thus made
with punches assume a very great importance in the manufacturing
and commercial world, as will perhaps be admitted when a few of
these are referred to.
The general character of a punch is that of a steel instrument,
the end of which is of precisely the form of the substance to be
removed by the punch, and which instrument is forcibly driven
through the material by the blow of a hammer. When the sub-
ject is entertained in a moderately extended sense, it will be seen
that much variety exists in the forms of the punches themselves,
and also in the modes by which the power whereby they are
actuated is applied.
So far as relates to the actual edges of the punches by which the
materials are severed, they may be classed under two principal di-
visions, namely, duplex punches, and single punches. The duplex
punches have rectangular edges and are used in pairs, often just
the same as in shears for metal. The single punches have some-
times rectangular but generally more acute edges, the one side
being mostly perpendicular.
The single punches require a firm support of wood, lead, tin, cop-
per, or some yielding material, into which the edge of the punch
may penetrate without injury, when it has passed through the
material to be punched.
The following classification has been attempted, as that best cal-
culated to throw into something like order the miscellaneous instru-
ments that will presently 'be more or less fully described.
Punches used without guides.
Punches used with simple guides.
Punches used in fly presses, and miscellaneous examples of their
products.
Punching machinery used by engineers.
It would be hardly admitted that a carpenter's chisel, driven by
a mallet through a piece of card, could be considered as a punch,
still the circular punch used with a mallet on a block of lead, for
cutting out circular disks of cards for gun- wadding, is indisputably
a punch, and yet scarcely more than a chisel bent round into a
hoop. The gun-punch is formed as in Fig. 337, and is turned
conical without and cylindrical within, or rather a little larger at
the top, that the waddings may freely ascend, and make their way
out at the top through the aperture ; when, however, annular
punches exceed about 2 inches in diameter, it is found a stronger
and better method to make them as steel rings, attached to iron
stems or centres spread out at the ends to fill the rings, as in Fig.
338, but holes are then required to push out the disks that stick to
the punch, as shown by the section beneath the figure 338.
The punch used in cutting, out wafers for letters is nearly simi-
lar, it being formed as a thin cylindrical tube of steel, fitted to the
end of a perforated brass cone having at the top two branches for
the cross handle, by which .it is pressed through several of the
372
THE PRACTICAL METAL-WORKER'S ASSISTANT.
farinaceous sheets, and as the wafers accumulate in the punch they
escape at the top. Confectioners use similar cutters in making
lozenges, and frequently the thin steel cutter is fixed to a straight
perforated handle of wood. The lozenges are cut out singly and
with a twist of the hand.
When the disk is the object required, the punchas always cham-
ferred exteriorly, as then the edge of the disk is left square and the
external or wasted part is bruised or bent ; but the punch is made
cylindrical without, and conical within, when the annulus or exter-
nal substance is required to have a keen edge. And when pieces
such as washers, or those having central holes, are required in card
or leather, the punches are sometimes constructed in two parts, as
shown separated in Fig. 339, the inner being made to fit the outer
punch, and their edges to fall on one plane ; so that one blow effects
the two incisions, and the punches may then be separated for the
removal of the work, should it stick fast between the two parts of
the instrument.
Punches of irregular and arbitrary forms, used for cutting out
paper, the leaves for artificial flowers, the figured pieces of cloth
for uniforms and similar things, are made precisely after the manner
of Fig. 337, and also of Fig. 338, except that they are forged in the
Figs. 337
339
341.
solid, or without the loose ring. These irregular punches are,
however, much more tedious to make than the circular, which
admit of being fashioned in the lathe.
Figured punches of much larger dimensions have been of late
used for cutting out the variously formed papers used in making
envelopes for letters. The punch or cutter is sometimes made in
one piece as a ring an inch to an inch and a half deep, or else in
several pieces screwed around a central plate of iron, and when the
punch is sharp it is really forced through three to five hundred
thicknesses of paper, by the slow descent of the screw press in
which it is worked. Army clothiers use similar instruments for
cutting out the leather for shoes and various other parts of military
clothing, and several of these punching or cutting tools are often
grouped together.
Proceeding to the punches used for metal, those having the
PUNCHES.
373
thinnest edges are known as hollow punches ; they are turned of
various diameters, from about J- to 2 inches, and of the section
Fig. 340 ; they are always used on a block of lead, and sometimes
for two or three thicknesses at a time of tinned iron, copper, or
zinc, Punches 341, smaller than J inch, are generally solid, quite
flat at the end, and are also used on a block of lead, which, although
it gives a momentary support, yields and receives into its surface
the little piece of metal punched out by the tool.
Fig. 343 represents the punch used by smiths for red-hot iron ;
the tool is solid and quite flat at the end, and whether it is round,
square, or oblong in its section, as for producing the holes repre-
sented, it is parallel for a short distance, then gradually enlarged,
and afterwards hollowed for the hazel rod by which it is surrounded
to constitute the handle. The smith's punch is frequently used
along with a bottom or bed tool known in this case as a bolster, and
which has a hole exactly of the same area as the section of the
punch itself.
Punches when used in combination with bolsters are clearly
similar in their action to the shears with rectangular edges, as will
Figs. 342 343
344
be seen on comparing Figs. 342 and 343, the only difference being
that the straight blade of the shears is to be considered as bent
round into a solid circle for a circular punch, or converted into a
square, rectangular, or other figure, as the case may be ; but every
part of the punch should meet its counterpart or the bolster in
lateral contact, the same as formerly explained in reference to shears.
This supposes the tools to be accurately made and correctly held
by the smith, but which is somewhat difficult, because the bolster,
the work, and the punch, are all three simply built up loosely upon
the anvil, and the eye can render but little judgment of their rela-
tive positions ; the punch is consequently apt to be misdirected so
as to catch against the bolster and damage both tools. The mode
so'hietimes used to avoid this inconvenience is represented in Fig.
344, in which a guide is introduced to direct the punch ; but agreea-
bly to the proposed arrangement, this figure will be more fully
explained hereafter, when some other tools of a lighter description
have been spoken of.
374
THE PRACTICAL METAL-WORKERS ASSISTANT.
Fig. 315 shows a punch used by harp-makers and others in cut
ting long mortises in sheet metaL The punch is parallel in thick-
ness, and has in the centre a square point from which proceed
several steps ; this punch is used with a bolster having a narrow
slit as long as the width of the punch. A small hole is first drilled
in the centre of the intended mortise ; the first blow on the punch
converts this into a square, the next cuts out two little pieces ex-
tending the hole into a short mortise, and each successive blow cuts
out a little piece from each end, thereby extending the mortise if
needful to the full width of the punch. From the graduated action
the method entails but little risk of breaking the punch or bulging
the metal, even if it should have but little width. Sometimes, to
make the punch act less energetically at- the commencement of
its work, the steps at the point are made smaller both in height and
width ; the serrated edge then becomes curved instead of angular,
as shown.
PUNCHES USED WITH SIMPLE GUIDES. — Beginning this part of
the subject with the tools having the most acute edges, we have to
refer to the punch pliers, Fig. 346, fitted with round hollow punches
for making holes in leather straps and thin materials. Some pliers
of this kind have a small oval punch, terminating in a chisel edge,
for cutting those holes that have to be passed over buttons ; and
pliers have been made with circular, square and triangular punches
for the cruel practice of marking sheep in the ear. In all these
tools the punch is made to close upon a small block of ivory or
copper, so as to insure the material being cut through without
injuring the punch.
Another example of slender chisel-like punches is to be seen in
the machine for cutting the teeth of horn and tortoise-shell combs.
The punch or chisel is in two parts, slightly inclined and curved at
the ends, to agree in form with the outline of one tooth of the
comb. The cutter is attached to the end of a jointed arm, moved
up and down by a crank, so as to penetrate almost through the
material, and the uncut portion is so very thin that it splits through
at each stroke and leaves the two combs detached.
Figs. 346
347.
The little instrument called a pen-making machine, is another
ingenious example of punches moving on adjoint. It is repre-
sented of half its true size, and ready to receive the pen, in
Fig. 347, and in Fig. 34o the two cutters are shown of full size and
PUNCHES. 37
* t
laid back in a right line— although in reality it only opens to a
righi angle.' The lower half has a small steel cutter b, pointed t<x ^
the angle of the nibs of the pen, and fluted to the curve of the / ') -
quill as at a ; the upper cutter d is made as an inverted angle with fj
nearly vertical edges, as seen at e, which exactly correspond with
the lower cutter, so as between them to cut the shoulders of the
pen. The upper tool also carries a thin blade or chisel, which
penetrates nearly through the quill and forms the slit.
The quill having been pared down to its central line, is inserted
through the hollow joint, on the line /, and the cutters being very
near the joint, the lever on being closed gives abundant power
for the penetration of the punches. The pen requires to be after-
wards nibbed, and for which purpose another cutter is attached to
the instrument, which has likewise an ordinary pen-blade, so as to
be entirely complete in itself.
Passing from the punches with guides obtained by means of
joints, and actuated by the pressure of the fingers, we will return
to Fig. 344, on page 373, which with its simple guide becomes a
very effective tool sometimes known as the hammer press, in con-
tradistinction to the screw, or fly-press to be hereafter spoken of.
The guide in the contrivance, Fig. 344, is a strong piece of iron
attached to the bottom tool, and sufficiently above it to admit the
work between the two. Each part is pierced with a hole of ex-
actly the same size, and accurately formed as if they were inter-
rupted portions of the same hole. The punch is made exactly to
fit either hole, so that from the upper it receives a correct guid-
ance, and it therefore cuts through the material, and penetrates the
lower piece, with a degree of precision and truth scarcely attain-
able when the tools are unattached, and are used simply upon the
anvil, as before described.
As however the punch mostly sticks tight in the work, it is
needful to turn the instrument over, and drive out the punch with
a drift a little smaller than the punch, and on which account punch-
ing tools of this kind are often made of two parallel plates of steel
firmly united by screws or steady pins, yet separated enough for
the reception of the work, and frequently contrivances are added
to guide the works to one fixed position, in order that any number
of pieces may be punched exactly alike. *
Thus in punching circular mortises, as in the half of a pair of
inside and outside callipers a, Fig. 349, the punch c, is first used to
produce the central hole, and this punch is then left in the bed b,
to retain the work during the action of the second punch m, by
which the mortise is cut. The punch m, is very short, to avoid
the chance of its being broken, and it is also narrow, so as to em-
brace only a short portion of the mortise, which is then completed,
with little risk to the tool, at three or four strokes, whilst the
punch c serves as a central guide.
Occasionally also punches of this simple kind, but on a larger
scale, have been placed under drop hammers, falling from a con-
376
THE PRACTICAL METAL-WORKER'S ASSISTANT.
siderable height through guide rods, somewhat as in a pib-driving
machine. This mode of obtaining power is not suited to the action
of punches used in cutting out metals, amongst other reasons, be-
cause the punch sticks very hard in the perforation it has made,
and requires some contrivance for pulling it out, which is not so
easily obtained in this apparatus as in fly-presses, that are suited
alike to large and small works.
The drop hammer, or as it is more commonly called a force, is
however very much used in the manufacture of stamped works,
or such as are figured between dies, of which an example is de-
scribed at length in page 312. Compared with a fly-press of equal
power, the force is less expensive in its first construction, but it is
also less accurate in its performance.
Fig. 350 is a very simple yet effective tool, which may be viewed
as a simplification of the fly-press i it consists of one very strong
piece of wrought-iron, about one inch thick and four or five inches
Figs. 349
wide, thickened at the ends and bent into the form represented ;
the one extremity is tapped to receive a coarse screw, the end of
which is formed as a cylindrical pin, or punch, that is sometimes
made in the solid with a screw, but more usually as a hardened
steel plug inserted in a hole in the screw. Immediately opposite
to the punch is another hole in the press, the extremity of which
is fitted with a hardened steel ring or bed punch. When the screw
is turned round by a lever about three feet long, it will make holes
as large as } inch diameter in plates f inch thick, and is therefore
occasionally useful to boiler makers for repairs, and also for fitting
works in confined situations about the holds of ships, and other
purposes. When this screw is turned backwards the punch is
drawn out and relieved from the work, but the screwing motion is
apt to wear out the end and side of the punch, and therefore to
alter its dimensions.
A very convenient instrument of exactly the same kind is used
in punching the holes in leather straps, by which they are laced
together with leather thongs, or united by screws and nuts, to con-
stitute the endless bands or belts used in driving machinery. In
this case the frame of the tool is made of gun-metal, and weighs
only a few ounces, the end of the screw is formed as a cutting
punch, and it is perforated throughout, that the little cylinders of
PUNCHES.
377
leather may work out through the screw, which only requires a
cross handle to adapt it to the thumb and fingers.
In this case the screwing motion is desirable, as the punch in
revolving acts partly as a knife, and therefore cuts with great
facility, as the leather is supported by the gun- metal which consti-
tutes the clamp or body of the tool.
PUNCHES USED IN FLY-PRESSES, AND MISCELLANEOUS EXAM-
PLES OF THEIR PRODUCTS. — The punches used in fly-presses, do
not differ materially from those already described, but it appears
needful to commence this section with some explanation of the
principal modifications of the press itself. The fly-press is a most
useful machine, which, independently of the punch or dies where-
with it is used, may be considered as a means of giving a hard,
unerring perpendicular blow, as if it were a powerful well-directed
hammer. The precision of the blow is attained by the slide where-
by the punch is guided, the force of the blow by the heavy revolv-
ing fly attached to the screw of the press. When the machine is
used, the fly is put in rapid motion, and then suddenly arrested by
the dies or cutters coming in contact with the substance submitted
to their action. The entire momentum of the fly, directed by the
agency of the screw, is therefore instantaneously expended on the
work to be punched or stamped, and the reaction is frequently
such as to make the screw recoil to nearly its first position.
The bare enumeration of the multitude of articles that are par-
tially or wholly produced in fly-presses, would extend to consid-
erable length, as this powerful and rapid auxiliary is not only
employed in punching holes, and cutting out numerous articles
from sheets of metal and other materials, but also in moulding,
stamping, bending or raising thin metals into a variety of shapes,
and likewise in impressing others with devices, as in medals and
coins.
Fig. 351 represents a fly-
press of the ordinary construc-
tion that is used for cutting
out works, and is thence called
a cutting press, in contra-dis-
tinction to the stamping or
coining presses. It will be
seen that the body of the
press, which is very strong, is
fixed upon a bed or base that
is at right angles to the screw ;
the latter is very coarse in its
pitch, and has a double or
triple square thread, the rise of
which is from about one to six
inches in every revolution.
The nut of the screw is mostly
of gun-metal, and fixed in the
Fig. 351.
a
378 THE PRACTICAL METALWORKER'S ASSISTANT.
upper part or head of the press. The top of the screw is square
or hexagonal, and carries a lever of wrought iron, terminating in
two solid cast-iron balls, that constitute the fly, and from the lever
the additional piece h, descends to the level of the dies to serve as
the handle, so that the left hand may be used in applying the material
to be punched, whilst the right hand of the operator is employed
in working the press.
The screw is generally attached to a square bar called the fol-
lower, which fits accurately in a corresponding aperture and is
strictly in a line with the screw ; and to the follower is attached
the punch shown detached at a. The punch is sometimes fitted
into a nearly cylindrical hole, and retained by a transverse pin or
a side screw, but more generally the die is screwed into the fol-
lower, like the chucks of some turning lathes ; the bed or bottom
die c, which is made strictly parallel, rests on the base of the press,
and is retained in position by the four screws, that pass through
the four blocks called dogs; these screws, which point a little
downwards, allow the die to be accurately adjusted, so that the
punch may descend into it without catching at any part, and
thereby inflicting an injury to the tools.
The piece b, which rests nearly in contact with the die, is called
the puller off, it is perforated to allow free passage to the punch ;
when the latter rises, it carries up with it for a short distance the
perforated sheet of metal that has been punched through, but
which is held back by the puller off) whilst the punch continuing
its ascent rises above the puller off) and leaves behind the sheet of
metal so released; the sheet is again placed in position whilst
another piece is punched out, and so on continually.
Before proceeding to speak of some of the works produced in
stamping presses, it is proposed to describe some of the points of
difference met with in fly-presses.
The body of a cutting press is in general made with one arm,
as represented in Fig. 351, because the sheet of metal can be more
freely applied to the die ; but stamping and coining presses, which
are used for pieces that have been previously cut out, require
greater strength and have two arms, or are made somewhat as a
strong lofty bridge with the screw in the centre.
The fly of the press is frequently made as a heavy wheel, which
may be more massive and is less dangerous to bystanders than the
lever and balls, and in large presses there are two, three, or four
handles fixed to the rim, as many men then run round with the
fly, and let go when the blow is struck.
Fly-presses are variously worked by steam-power ; thus in the
mint the twelve presses for cutting out the blanks or disks for
coin, are arranged in a circle around a heavy fly-wheel, which re-
volves horizontally by means of the steam-engine. The wheel has
one projecting tooth or cam, which catches successively the twelve
radial levers fixed in the screws of the presses, to cut the blanks,
and twelve springs immediately return the several levers to their
first positions, ready for the next passage of the earn on the wheel
PUNCHES.
379
The fly and screw are also worked by power, in some cases by
an. eccentric or crank movement fixed at a distance ; a long con-
necting-rod then unites *the crank to an arm of the wheel, or to a
straight lever, and gives it a reciprocating movement.
At other times, in place of the crank motion are ingeniously
substituted a piston and cylinder worked after the manner of an
oscillating steam-engine, if we imagine the boiler to be superseded
by a large chamber, exhausted by the steam-engine nearly to a
vacuum, thus constituting an air engine, the one side of the piston
being opened for a period to the exhausted chamber, whilst the
other receives the full pressure of the atmosphere.
In the manufacture of steel pens, it is important to have an
exact control over the punches which cut the slits, and those which
mark the inscriptions, as by descending too far they might dis-
figure the steel, or even cut it through. Accordingly there is in-
troduced between the head of the press and the lever an adjusta-
ble ring, which acts as a stop, and only allows the punches to
descend to one definite distance, until in fact the ring is pinched
between the press and lever.
The screw of the fly-press is sometimes superseded by a contriv-
ance known both as the toggle joint, and as the knee joint. The
two parts a, I, and b, c, Fig. 352 are joined to each other at b, the
Figs. 352
353.
extremity a, is joined to the upper part of the press,' and c, to the
top of the follower. When the parts a, b, and b, c, are inclined at
a small angle, the extremities, a, and c; are brought closer together,
and raise the follower, but when the two levers are straightened, a
and c separate with a minute degree of motion, but almost irre-
sistible power, especially towards the completion of the stroke.
The bending and straightening of the toggle joint is effected by
the revolution of a small crank, united to the point b, Fig. 352, by
a connecting rod b,f.
Presses with the toggle joint are perfectly suited to cutting out
works with punches and bolsters, provided the relative thickness
380 THE PRACTICAL METAL-WORKER'S ASSISTANT.
of the work and tools are such as to bring to bear the strongest
point of the mechanical action, at the moment the greatest resist-
ance occurs in the work ; but as the fly-pre*ss with a screw is in all
cases powerful alike, irrespective of such proportions, provided
alone that there is sufficient movement to create the required
momentum, the fly-press is more generally useful.
The cut 353 refers to a lever press worked by an eccentric, and
used in cutting brads and nails, which will be again alluded to
when this manufacture is briefly noticed.
It is now intended to describe a few examples of works executed
in fly-presses, giving the preference to those appertaining to
mechanism.
The round disks of metal for coin are always cut out with the
fly-press, and are then called blanks, the punch being a solid
cylinder, the bed or bolster a hollow cylinder that exactly fits it.
In the gold currency, more especially, great care is taken to make
these punches as nearly as it is possible mathematically alike in
diameter, and the sheets of gold also mathematically alike in thick-
ness, by aid of the drawing rollers or rather drawing cylinders
referred to in page 327 ; bat notwithstanding every precaution,
the pieces or blanks when thus prepared do not always weigh
strictly alike. This minute difference is most ingeniously remedied
by using the one error as a compensation for the other. Trial is
made at each end of every strip of gold; and by cutting the thicker
gold with the smaller punches, the adjustment is effected with the
needful degree of accuracy, so that every piece is made critically
true in weight, without the tedious necessity for weighing and
scraping, otherwise needful.
Buttons are made in enormous quantities by means of the fly-
press. That metal buttons should be thus cut out with tools and
stamped with dies, will be immediately obvious to all, but the fly-
press has been also more or less employed in making buttons of
horn, shell, wood, papier-mache, and some other materials. Amongst
others, may be noticed the silk buttons, called Florentine buttons,
each of which consists of several pieces that are cut out in presses,
then enveloped by the silk covering, and clasped together at the
back (in the press), by a perforated iron disk, the margin of which
is formed into 6 or 8 points that clutch and hold the silk, whilst
the cloth by which the button is sewed on, is at the same time pro-
truded through the centre hole in the back plate of the silk button ;
details that may be easily inspected by pulling one oF them to
pieces. Indeed great ingenuity has been displayed, and many
patents have been granted, for making this necessary article of
• dress, a button.
Round washers that are placed under bolts and nuts in machin-
ery, are punched out just like the blanks for coin ; although in
punching the larger washers, that measure 5 and 6 inches in diam-
eter and J inch thick, with the. ordinary fly-presses, the iron
requires to be made red hot.
PUNCHES.
381
The round or square holes in the washers are made at a second
process with other tools, and to insure the centrality of the holes,
some kind of stop is temporarily affixed Jx> the lower tool. The
more complete stop is a thin plate of iron hollowed out at an angle
of from 90 to 120 degrees and screwed on the top of the bed, as this
may be set forward to suit various diameters. But the more usual
plan is to drill two holes in the bed, to drive in two wires, and to
bend their ends flat down towards the central hole, as also shown
in Fig. 354 ; the end of the wires are filed away until, after a few
trials, it is found the blank, when held in contact with the stops
by the left hand, is truly pierced ; the whole quantity may be then
proceeded with as rapidly as the hands can be used, with confi-
dence in the centrality of all the holes thus produced.
Chains with flat links that are used in machinery are made in
the fly -press. The links are cut out of the form shown at a, Fig.
355, the holes are afterwards punched just as in washers and one at
a time, every blank being so held that its circular extremity touches
the stops on the bed or die, and thereby the two holes become equi-
distant in all the links, which are afterwards strung together by
inserting wire rivets through the holes.
The pins or rivets for the links are cut off from the length of
wire in the fly-press, by a pair of cutters like wide chisels with
square edges, assisted by a stop to keep the pins of one length ;
or by one straight cutter and an angular cutter hollowed to about
60 degrees^ or by two cutters each hollowed to 90 degrees. In
the three cases, the wire is respectively cut from two, three, or
four equidistant parts of its circumference : semicircular cutters
are also used. The straight cutters first named, are moreover very
usefully employed in the fly-press for many of the smaller works,
that would otherwise be done with shears.
Sometimes the succession of the links for the chain, is one and
two links alternately, as at b, Fig. 355 ; at other times 3 and 2, or
4 and 3 links, as at c, and so forth up to about 9 and 8 links alter-
355
357.
nately, which are sometimes used, and the wires when inserted are
slightly riveted at the ends.
The pin is generally the weakest part of the chain and gives
way first, but in the chains with 8 or 9 links, the pin must be cut
through at 16 places simultaneously, before the chain will yield.
382 THE PRACTICAL METAL-WORKERS ASSISTANT.
Chains are sometimes intended to catcli on pins or projections,
around a wheel of the kind shown in Fig. 357, to fulfil the office
of leather bands, withou^ the possibility of the slipping, which is
apt to occur with bands when subjected to unusual strains.
Such chains are made after the manner shown in Fig. 356 : to
constitute the square openings that fit over the pins of the wheel,
the central links are made shorter, by which means the apertures
are brought closer together than if the longer links were used
throughout. Fig. 358 shows a different kind of chain, that has
been used for catching in the teeth of an ordinary spur-wheel with
epicycloidal teeth: this chain was invented by John Oldham, Engi-
neer to the Bank of Ireland.
Chains for watches, time-pieces, and small machinery, are too
minute to be made as above described, therefore the slip of steel
is first punched through with the rivet holes required for a num-
ber of links, by means of a punch in which two steel wires are
inserted ; the distance between the intended links is obtained
(somewhat as in file cutting) by resting the burrs of the two pre-
vious holes against the sharp edge of the bed or bolster. The
links are afterwards cut out by a punch and bolster of the kind
already noticed, but very minute, and the punch lias two pins in-
serted at the distance of the rivet holes, the slip of steel being
every time fitted by two of the holes to these pins ; all the links
are thereby cut centrally around the rivet holes.
The tools are carried nra thick block having a perpendicular
square hole, fitted with a stout square bur ; the lattf r is driven
with a hammer, which is supported on pivots, raised by a spring,
and worked by a pedal ; but when the links measure from J to J
an inch in length, such tools are worked by a screw.
The punches are fitted to the side of the square bar, in a pro-
jecting loop or mortise, and secured by a wedge. They are drilled
with holes for the pins, and across each punch there is a deep
notch to expose the reverse ends of the pins, in order that when
broken they may be driven out and replaced. The pins are taper
pointed, that they may raise burrs, instead . of cutting the metal
clean out, and being taper, no puller-off is required, and the bed
tools are fitted in chamfer grooves in the base of this old yet very
efficient instrument.
A large chain for a pocket chronometer now before the author,
measures nearly 14 inches in length, and contains in every inch of
its length 22 rivets and also 33 links, (in three rows) ; the total
number of pieces in the chain is therefore 770, and its weight is
9 J grains. A chain for a small pocket- watch measures 6 inches in
length, and has 42 rivets and 63 links in every inch, in all 630
pieces, and yet the entire chain only weighs one grain and three-
quarters.
The square links of chains for jewelry are often cut out with
punches, the exterior and interior being each rectangular ; after
which each alternate link is slit with a fine saw for the introduc-
PUNCHES. 383
tion of the two contiguous links, and then soldered together so
that the gaps become filled up. Other chains are drawn as square
tubes, and cut off in short lengths with a saw ; these, after having
been strung together, are often drawn through a draw-plate with
round holes, to constitute chains which present an almost continu-
ous cylindrical surface like round wire ; a very neat manufacture,
invented in France.
The teeth of saws are for the most part cut in the fly-press.
Teeth, whether large or small, require but one punch, the sides of
which meet at 60 degrees. Two studs are used to direct the edge
of the blade for the saw to the punch, at the required angle de-
pending on the pitch or inclination of the teeth, and an adjustable
stop determines the space or interval from tooth to tooth, by catch-
ing against the side of the last tooth previously made. Gullet
teeth, and the various other kinds shown, require punches of their
several compounded figures, and of different dimensions for each
size of tooth.
The teeth of circular saws are similarly punched out by mount-
ing the perforated circular disk on a pin or axis, but in cutting the
last six or eight teeth, it is needful to be watchful, so as to divide
the remaining space into moderately equal parts.
In cutting the teeth of circular saws not exceeding 12 inches
diameter, Holtzapffel and Co. have been in the habit of mounting
the steel plates on a spindle in a lathe with a dividing plate, and
using a punch and bed fitted to a square socket fixed horizontally
in the ordinary rest or support for the turning tool, the punch being
driven through the plate by one revolution of a snail or cam, by
means of a winch handle, and thrown back by a spring. In this
arrangement the dividing plate insures the exact dimensions and
equality of the teeth, which are rapidly and accurately cut.
The copper caps for percussion guns are punched out in the form
of a cross with short equal arms, or sometimes in a similar shape
with only three arms, and the blanks, after having been annealed,
are thrown out into form by means of dies, which fold up the arms
and unite them to constitute the tubular part, whilst the central
part of the metal forms the top of the cap that receives the com
position and sustains the blow of the hammer.
Steel pens are another most prolific example of the result of the
fly-press ; they pass through the hands many times, and require to
be submitted to the action of numerous dies, to five of which alone
we shall advert. The blanks are cut by dies of the usual kind, so
as in general to produce a flat piece of the exterior form of
Fig. 359, page 384 ; the square mortise at the bottom of the slit
is then punched through. The next process is usually to strike on
the blanks the maker's name.
The slit is now cut by a thin chisel-like cutter, which makes an
angular gap nearly through the steel, from that side of the metal
intended to form the inner or concave part of the pen, and the act
of curling up the pen into the channeled form, brings the angulai
384
side of the groove into contact, rendering the slit almost invisible.
The slit, Which is as yet only part way through the pen, is in
general completed in the process of hardening, as the sudden
transition into the cooling liquid generally causes the little portion
yet solid to crack through, or else the slit remains unfinished
until the moment the pen is pressed on the nail to open and ex-
amine its nibs.
Lariviere's perforated plates for strainers, lanterns, meat safes,
colanders, and numerous other articles, exhibit great delicacy and
accuracy in the mode in which they are punched out. The tools
are illustrated by the enlarged sections, Fig. 360. The punch con-
sists of a* plate of steel called the punch plate, which is in some
361.
cases pierced with only one single line of equidistant holes, that
are countersunk on their upper extremities. Every hole is filled
with a small cylindrical puncK made of steel wire, the end of
which is bumped up, or upset to form a head, that fills the chamfer
in the punch plate, so that the punch cannot be drawn out by the
work in the ascent of the press. The bed punch or matrix has a
number of equidistant holes corresponding most exactly with the
punches. In this case the holes in the work are punched out one
line at a time, and between each descent of the punches the sheet
of metal is shifted laterally by a screw slide until it is in proper
position to receive the adjoining line of holes.
At other times, the tool, instead of having only one line of
punches, is wide, and entirely covered with several lines, so as to
punch some hundreds or even thousands of holes at one time.
For circular plates the punches are sometimes arranged in one
radial line, but more usually the whole of the punches required for
the fourth, sixth or eighth part of the circular disks are placed in
the form of a sector, and the central hole, having been first
punched, is made to serve as the guide for the four, six or eight
positions at which these beautiful tools are applied.
Many of the thin plates thus punched require to be strained like
the head of a drum to keep the metal flat, in which case the metal
is grasped between little clamps or vices around its four edges, and
then stretched by appropriate screws and slides with which the
apparatus is furnished, and the same mechanism prevents the metal
from rising, and therefore fulfils the office of the puller-off com-
monly used with punches.
PUNCHES. 885
The construction of the tools above described calls for the great-
est degree of precision. The drill employed to pierce the punch
and matrix is of exceedingly small size in the finest perforated
works, as it is said as many as six or seven hundred holes have
been inserted in the length of six inches, which, considering the
intervening spaces to be half as wide as the diameter of the holes,
would make the latter of the minute size of only six-thousandths
of an inch diameter. Such finely perforated metal appears to offer
nearly the transparency of muslin, and is a manifest proof of the
great skill displayed in the construction of the instruments, and in
conducting the entire process.
M. Marc Lariviere's patent was granted 28th Nov., 1825, and is
described in the Repertory of Patent Inventions, vol. iii., 3d series,
page 182.
All the foregoing examples of punched works suppose the punch
to have been fixed to the follower of the press, and the matrix to
the base of the same, in which case the bed punch requires to be
very exactly adjusted by the set screws or dogs of the press. But
it remains, in concluding this section, to advert to a different
arrangement, in which the cutting tools are quite detached, and are
far less liable to accident or fracture, even when the punches are
of very large area and complicated figure, than when constructed
in the ordinary manner with a shank, by which they are united to
the follower of the press.
Punches, to be used in this manner, for works with various de-
tached apertures requiring any especial arrangement, and for
various straggling and complicated objects, are constructed as shown
in Figs. 362 to 364. There are two steel plates somewhat larger
than the work, and from -fs to f thick, the plates are hinged
together like the leaves of a book, but are placed sufficiently distant
to admit between them the work to be stamped out, and which is
pinched between them by a thumb screw a. The two plates whilst
folded together are perforated with all the apertures required in
the work, which perforation may be either detached, continuous or
arranged in any ornamental design that may be required. To all
the apertures are fitted punches, which in length or vertical height
are about one-eighth of an inch longer than the thickness of the
upper plate, so as to stand up one-eighth when resting on the ma-
terial to be punched, as seen in the partial section 36-i, in which the
work is shaded obliquely and the punch Vertically.
As it would be difficult to fit the punches in one single piece to
the ornamental or straggling parts of some devices, and as moreover
such large and complicated punches would be almost sure to become
distorted in the hardening, or broken when in use, the difficulty is
boldly met by making the punch of as many small pieces as cir-
cumstances may render desirable, but which pieces must, collectively
fill up all the interstices of the plate.
In using these punching tools, it is only necessary first to fix
between the plates the metal to be pierced, then to insert all the
25
386
THE PRACTICAL METAL-WORKER S ASSISTANT.
punches into their respective apertures, and lastly to give the wholo
one blow between the flat disks of a powerful fly-press ; this drives
all the punches through the work, and leaves them flush with the
upper surface. The whole is then removed from the press, and
placed over an aperture in the work bench, and with a small drift
and hammer the punches are driven out of the plates into a drawer
beneath, and on the plates being separated, the work will be found
to be exactly perforated to the same design as that of the tool itself ;
or with any part of the design instead of the whole, if part only of
the punches were inserted in their respective places. The punches
are selected from amidst the corresponding pieces of brass, which
latter are laid on one side and the routine is recommenced.
It is by this ingenious application of punches that the beautiful
buhl works of the late Robert B. Henesey, of Holborn, London,
were stamped. If a honeysuckle should be the device, the piece
of brass is first placed between the plate and punched out, and pro-
vided the punches are of the same length, the honeysuckle is re-
moved in one piece although the punch may be in several ; the wood
is afterwards inserted, and is punched to exactly the same form, so
that the brass honeysuckle will be found to fit in the most perfect
manner, as it is an exact counterpart of the removed wood.
The process is very economical and exact, but is only suited to
large designs, because of the injury it would otherwise inflict on
the wood, and on account of the expense of the tools, the mode is
only proper for those patterns of which very large numbers are
wanted ; whereas the buhl saw is not liable to these limitations, but
is of universal, although less rapid application.
Figs. 362
366.
Cut brads and nails, or those which, instead of being forged, are
cut out of sheet iron by machinery, constitute the last example it
is proposed to advance in this section.
Brads of the most simple kind, as in Fig. 365, have no heads,
but are simply wedge form, and are cut out of strips of sheet iron,
equal in width to the length of the brads : these strips are slit with
circular shears, transversely from the ends of 'the sheets of iron, so
that the fibre of the iron may run lengthways through the nails.
When such brads are cut in the fly -press, the bed has a rectangu.
PUNCHES. 887
Jar mortise shown by the strong black line in Fig. 365, the punch
is made rather long and rectangular so as exactly to fill the bed,
but the last portion of the punch, say for half an inch of its length,
is nicked in, or filed back exactly to the size and angle of the brad,
as shown in the inverted plan, in which the shaded portion shows
the reduced part or tail of the punch. The punch is never raised
entirely out of the bed, in order that the strip of metal may be put
so far over the hole in the bed as the tail of the punch will allow
it, and also in contact with a stop or pin fixed to the bed, and in
the descent of the punch its outer or rectangular edge moves the
brad.
The strip of metal is turned over between every descent of the
press, so as to cut the head of the one brad from the point of that
previously made, and the double guides afforded by the tail and
stop enable this to be very quickly and truly done. The upper
surface of the bed is not quite horizontal but a little inclined, so
that the cutting may commence at the point of the brad, and thereby
curl it less than if the tools met in absolute parallelism.
In cutting brads that have heads, the general arrangements are
somewhat different, as explained in the diagram Fig. 366, in which
as before, the rectangular aperture in the bottom tool is bounded
by the strong black line, the tail of the punch is shaded, the stop s,
is situated as far beyond the aperture in the bed as the vertical
height of the head, and it is so made that the small part which ex-
tends to the right, overhangs the slip of iron that is being cut, after
the manner of a puller-off ; but the overhanging part only comes
into action when the slip is tilted up, either by accident, or from
being so short as to give an insufficient purchase for the hand. It
is also to be observed that the width of the point of the brad is just
equal to the projection of its head.
On the end of the strip of iron being first applied, a wedge-form
piece is cut off, exactly equal to the difference between the tail of
the punch and the bed, and a little projection is left near s, and
which projection, after the iron is turned over, rests against the tail
of the punch, as shown in the figure, so that the succeeding cut re-
moves the one brad and forms the head of the following ; the tail
of the punch being inclined to the precise angle drawn from the
point to the head of the brad, as denoted in the diagram.
When, as it is more usual, brads are cut out by steam-power, the
cutters are not worked in a fly-press, but the moving cutter is com •
monly fixed at the end of a long arm which is moved rapidly up
and down by a crank ; the strip of metal is held in a spring clamp,
terminating in a long iron rod which rests in a Y or fork, so that
the boy who attends the machine, can turn the metal over very
rapidly between every alternation of the machine ; these particulars
are shown in Fig. 353.
The machine, Fig. 353, may be used for brads either with or
without heads ; it is, however, always necessary to turn the iron
over between every cut- but in the toggle press, Fig. 352, and
388 TIIE PRACTICAL METAL-WORKER'S ASSISTANT.
which acts much more quickly, it is not requisite to reverse the
metal, as the entire press is moved on its pivots e e, by the rod g.
so as to incline the press alternately to the right and left, to the
angle of such nails as are simply wedge-form, or have no heads, as
in Fig. 365, page 386.
In some machines resembling Fig. 353, the nail as soon as cut
off is grasped in a pair of forceps or dies, whilst a hammer, also
moved by the machine, strikes a blow that upsets the metal, and
constitutes the flat head in the kinds known as cut nails, and
tacks.
PUNCHING MACHINERY USED BY ENGINEERS. — After the re-
marks offered on pages 364 to 367, on shearing tools, little remains
to be said in this place on the punching machinery used by engi-
neers, as it was there stated that the cutters for shearing and the
punches, were most usually combined in the same machine ; the
punch being placed either at the outer extremity of the jointed
lever, or at the bottom of the slide in those machines having rec-
tilinear action. The punch is fixed to the slide or moving piece,
the die is secured to the framing by means of four holding and ad-
justing screws just as in fly-presses, and the puller off or stop is
likewise added, all which details are represented in the woodcuts
on pages 365 and 366.
The principal application of the engineer's punching engine, is
for making the rivet-holes around the edges of the plates of which
steam-boilers, tanks, and iron ships are composed. Another im-
portant use, and in which the punches trench upon the office of the
shears, is in cutting out curvilinear parts and apertures or panels
in boiler work, to which straight bladed shears cannot be applied.
In this case the round punch is used in making a series of holes
running into one another, along the particular line to be sheared
through, or in other words the punch is used as a gouge, by which
the hole that has been first formed, is extended by cutting away
crescent-form pieces, thus leading the incision in any required
direction.
This employment of the punch to shearing curved lines, is also
much used in cutting out the side plates of the framings of loco-
motive engines, which consist of two pieces of stout boiler plate
(the technical name for iron in sheets from J- to } inch thick), riveted
alongside a central piece of wood, that is sometimes also covered
above and below with iron, all the parts being united by rivets.
The punching engine serves admirably for cutting out all the curved
lines in these side plates, also the spaces where the bearings for the
wheels are situated, and various apertures.
Fig. 367 is a slotting and paring machine manufactured at the
Lowell Machine Shop, Mass. The base plate and upright frame
are of cast-iron. The tool bar moves by an adjustable crank of
ten-inch stroke. It will range over a wheel of four feet diameter.
Work may be executed by a circular or straight line movement.
The tool is made self-acting, and inclines, when necessary, from a
PUNCHES.
339
horizontal position to cut key grooves in tapering holes. The table
apparatus is adjustable up and down in front of the frame by means
of a rack, pinion worm, and worm-wheel.
Fig. 337.
In England the name of the inventor is suppressed of a very great
improvement in the punching engine, as applied to making boilers
and tanks, in which the rivet-holes are usually required to be made
in straight lines, and at exactly equal distances, so that holes in two
pieces punched separately may exactly correspond.
The plate was fixed down upon a long rectilinear slide or car-
riage, and during every ascent of the punch, was advanced by the
machine itself, the interval from hole to hole, the moment after the
punch was disengaged from the work. Subsequently 2, 3, or 4
punches were fixed at equal distances in the vertical slide, but the
punches were made of unequal lengths, so that they came succes-
sively into action, thereby dividing the strain, and the horizontal
slide was consequently shifted every time, a distance equal to 2, 3,
or 4 intervals. This machine, which displayed much ingenuity
of invention, served as the foundation of the more simple punch-
ing engines that are now met with. We believe the invention to
be by M. Cave* of Paris.
The following .experiments were performed with a cast-iron
lever, 11 feet long, multiplying the strain ten times, with a screw
390 THE PRACTICAL METAL-WORKER'S ASSISTANT.
adjustment at the head, and a counterpoise. The sheets of iron
and copper which were experimented upon, were placed between
two perforated steel plates, and the punch, the nipple of which was
perfectly flat on the face, being inserted into a hole in the upper
plate, was driven through by the pressure of the lever.
The average results of the several experiments (which are given
in a detailed tabular form), show that the power required to force
a punch half an inch diameter through copper and iron plates, is
as follows :
Iron plate 0.08 thick, required a pressure of 6,025 pounds.
0.17 " " 11,950
" 0.24 " " 17,100 "
Copper plate 0.08 " " 3,983 "
0.17 " " 7,883 "
Hence it is evident that the force necessary to punch holes of
different diameters through metal of various thicknesses, is directly
as the diameter of the holes and the thickness of the metal. A
simple rule for determining the force required for punching may
be thus deduced. Taking one inch diameter and one inch in thick-
ness as the units of calculation, it is shown that 150'00 is the con-
stant number for wrought-iron plates, and 96*000 for copper plates.
Multiply the constant number by the diameter in inches, and by
the thickness in inches ; the product is the pressure in pounds, that
will be required to punch a hole of a given diameter through a
plate of a given thickness.
It was observed that the duration of pressure lessened consider-
ably the ultimate force necessary to punch through metal, and that
the use of oil on the punch reduced the pressure about 8 per cent.
A drawing of the experimental lever and apparatus accompanied
the communication.
The second experiments were by means of a hydrostatic press
having four cylinders in combination, punching through various
pieces of iron; the thickest of them measured 3J inches thick, and
from which was punched out a disk of 8 inches diameter, with a
pressure of 2000 tons.
The removed piece was rather thinner than the remainder and *
little taper, which arose from the circumstance of the bolster hav-
ing been purposely made with a flat bottom, and a little larger in
diameter than the punch, so that the disk when removed was a
little spread or flattened out.
It is curious that experiments so distant from one another in
their scale of proportion, should yet agree so nearly :
The computed force is . . 150,000 x 8 x 3 J = 4,200,000 Ibs.
The actual force was ... 2000 x 20 x 112 =4,480,000 Ibs.
Figure 368 is an upright drill, manufactured at the Lowell ma-
chine shop, Lowell, Mass., and invented by W. B. Bennet, who has
invented many other useful metal-worker's tools.
PUNCHES.
391
. The base and frame are of cast-iron ; the table that holds the
work is elevated or depressed by a screw ; the drill feeds down by
hand; the drilling-shaft has four changes of speed, and geared
Pig. 368.
with iron cone pulleys. This instrument will drill a hole ten
inches from the nearest edge of the object operated upon, and six
inches deep.
Fig. 369 is the Universal Drilling Machine, manufactured at the
LowelJ Machine Shop, Lowell, Mass., of which establishment Wm.
A. Burke is superintendent.
This machine is designed for drilling pieces of castings, which,
from their size, cannot be operated upon by drilling machines of
the ordinary kinds. It consists of a very strong upright frame or
column, which carries upon its front side a heavy beam or arm,
that can be moved out from the column to the distance of 8 feet.
This beam has also a movement up or down of 6 feet, upon the
front of the column. It also carries upon its extreme outer end
the drill headstock. The spindle in this headstock is driven by
means of bevel gears and shafts from the first driving shaft. A
892
THE PRACTICAL METAL-WORKER'S ASSISTANT.
hole can be drilled in a piece 8 feet distant from the nearest side
or edge, and a piece can be brought under the drill 6 feet in height.
Fig. 369.
The headstock and spindle are made adjustable, so that the whole
can be drilled at any angle required, and ten inches deep. The
driving shaft with cast-iron pulleys is attached to the frame. The
machine is back geared, giving 8 different speeds to the drill.
CHAPTER XXII.
DRILLS.
DRILLS FOR METAL, USED BY HAND. — The frequent necessity,
in metal works, for the operation of drilling holes, which are re-
quired of all sizes and various degrees of accuracy, has led to so
very great a variety of modes of performing the process, that it is
difficult to arrange with much order the more important of these
methods and apparatus. t
The ordinary piercing drills for metal do not present quite so
much variety as the wood drills. The drills for metal are mostly
pointed ; they consequently make conical holes, which cause the
point of the drill to pursue the original line, and eventually to
produce the cylindrical hole. The comparative feebleness of the
drill-bow limits the size of the drills employed with it to about
one-quarter of an inch in diameter ; but as some of the tools used
with the bow agree in kind with those of much" larger dimensions,
it will be convenient to consider as one group the forms of the
edges of those drills which cut when moved in either direction.
DRILLS.
393
Figs. 370, 371, and 372, represent, of their largest sizes, the
usual forms of drills proper for the reciprocating motion of the
drill bow, because, their cutting edges being situated on the line
of the axis, and chamfered on each side, they cut, or rather scrape,
with equal facility in both directions of motion.
Fig. 370 is the ordinary double-cutting drill, the two facets
forming each edge meet at an angle of about 50 to 70 degrees, and
the two edges forming the point meet at about 80 to 100 ; but the
watch-makers, who constantly employ this kind of drill, sometimes
make the end as obtuse as an angle of about 120 degrees ; the
point does not then protrude through their thin works long before
the completion of the hole. Fig. 371, with two circular chamfers,
bores cast-iron more rapidly than any other reciprocating drill, but
it requires an entry to be first made with a pointed drill. By
. some this kind is also preferred for wrought-iron and steel. The
flat-ended drill, Fig. 372, is used for flattening the bottoms of holes.
Fig. 373 is a duplex expanding drill, used by the cutlers for in-
laying the little plates of metal in knife handles; the ends are
drawn full size.
Figs. 370 371 372
373
375.
Fig. 374 is also a double-cutting drill ; the cylindrical wire is
filed to the diametrical line, and the end is formed with two facets.
This tool has the advantage of retaining the same diameter when
it is sharpened. It is sometimes called the Swiss drill, and was
employed by M. Le Kiviere, for making the numerous small holes
in the delicate punching machinery for manufacturing perforated
sheets of metal and pasteboard. These drills are sometimes made
either semi-circular or flat at the extremity.
The square countersink, Fig. 375, is also used with the drill-
bow ; it is made cylindrical, and pierced for the reception of a
small central pin — after which it is sharpened to a chisel-edge, as
shown. This countersink is in some measure a diminutive of the
pin drills, Figs. 382 to 385 ; and occasionally circular collars are
fitted on the pin for its temporary enlargement, or around the
larger part to serve as a stop and limit the depth to which the
countersink is allowed to penetrate, for inlaying the heads of
screws. The pin is removed when the instrument is sharpened.
By way of comparison with the double-cutting drills, the ordi-
THE PRACTICAL METAL-WORKERS ASSISTANT.
nary forms of those which only cut in one direction are shown in
Figs. 376, 377, and 378. Fig. 376 is the common single cutting
drill for the drill-bow, brace, and lathe. The point, as usual, is
nearly a rectangle, but is formed by only two facets, which meet
the sides at about 80° to 85° ; and therefore lie very nearly jn con-
tact with the extremity of the hole operated upon, thus strictly
agreeing with the form of the turning tools for brass. Fig. 377 is
a similar drill, particularly suitable for horn, tortoise-shell, and
substances liable to agglutinate and clog the drill. The chamfers
are rather more acute, and are continued around the edge behind
its largest diameter, so that, if needful, the drill may also cut its
way out of the hole.
Fig. 378, although never used with the drill-bow, nor of so small
a size as in the wood-cut, is added to show how completely the drill
proper for iron, follows the character of the turning tools for that
metal ; the flute or hollow filed behind the edge, gives the hook-
formed acute edge required in this tool, which is in other respects
like Fig. 376 ; the form proper for the cutting edge is shown more
distinctly in the diagram a, Fig. 382.
Figs. 376
377
378
379
381.
Care should always be taken to have a proportional degree of
strength in the shafts of the drills, otherwise they tremble and
chatter when at work or they occasionally twist off in the neck ;
the point should be also ground exactly central, so that both
edges may cut. As a guide for the proportional thickness of the
point, it may measure at b, Fig. 379, the base of the cone, about
one-fifth the diameter of the hole, and at p, the point, about one-
eighth, for easier penetration ; but the fluted drills are made nearly
of the same thickness at the point and base.
In all the drills previously described, except Fig. 374, the size
of the point is lessened each time of sharpening ; but to avoid this
loss of size, a small part is often made parallel, as shown in Fig.
379. In Fig. 380 this mode is extended by making the drill with
a cylindrical lump, so as to fill the hole ; this is called the re-centering
drill. It is used for commencing a small ho!6- in a flat-bottomed
cylindrical cavity ; or else, in rotation with the common piercing
drill, and the half-round bit. in drilling small and very deep holes
DRILLS.
395
in the Lathe. Fig. 330 may be also considered to resemble the
slop-drill, upon which a solid lump or shoulder is formed, or a
collar is temporarily attached by a side screw, for limiting the
depth to which the tool can penetrate the work.
Fio\ 381, the cone countersink, may be viewed as a multiplication
of tlie common single cutting drill. Sometimes, however, the tool
is filed with four equi-distant radial furrows, directly upon the
axis, and with several intermediate parallel furrows sweeping at an
angle around the cone. This makes a more even distribution of
the teeth, than when all are radial as in the figure, and it is always
used in the spherical cutters, or countersinks, known as cherries,
which are used in making bullet-moulds.
On comparison, it may be said the single chamfered drill, Fig.
376, cuts more quickly than the double chamfered, Fig. 370, but
that the former is also more disposed of the two to swerve or run
from its intended position. In using the double cutting drills, it
is also necessary to drill the holes at once to their full sizes, as
otherwise the thin edges of these tools stick abruptly into the
metal, and are liable to produce jagged or groovy surfaces, which
destroy the circularity of the holes ; the necessity for drilling the
entire hole at once, joined to the feebleness of the drill-bow, limits
the size of these drills.
In using the single chamfered drills, it is customary, and on sev-
eral accounts desirable, to make large holes by a series of two or
more drills ; first the run of the drill is in a measure proportioned
to its diameter, therefore the small tool departs less from its in-
tended path, and a central hole once obtained, it is followed with
little after-risk by the single cutting drill, which is less penetra
Figs. 382
383
384
385.
B.tf -ffiafi '=£
tive. This mode likewise throws out of action the less f
part of the drill near the point, and which in large drills is neces-
sarily thick and obtuse ; the subdivision of the work enables a
comparatively small power to be used for drilling large hol«s, and
also presents the choice of velocity best suited to each progressive
diameter operated . upon. But where sufficient power can bd ob-
396 THE PRACTICAL METAL-WORKER' S ASSISTANT.
tained, it is generally more judicious to enlarge tlie holes previ-
ously made with the pointed drills, by some of the group of pin
drills, Figs. 382 to 385, in which the guide principle is very per-
fectly employed : they present a close analogy to the pjjig centre-
bit, and the expanding centre-bit, used in carpentry.
The ordinary pin-drill, Fig. 382. is employed for making counter-
sinks for the heads of screw-bolts inlaid flush with the surface, and
also for enlarging holes commenced with pointed drills, by a cut
parallel with the surface; the pin-drill is also particularly suited
to thin materials, as the point of the ordinary drill would soon
pierce through, and leave the guidance less certain. "When this
tool is used for iron it is fluted as usual, and a represents the form
of the one edge separately.
Fig. 383 is a pin drill principally used for cutting out large
holes in cast-ir.on and other plates. In this case the narrow cutter
removes a ring of metal, which is of course a less laborious pro-
cess than cutting the whole into shavings. When this drill is
applied from both sides, it may be used for plates half an inch and
upwards in thickness ; as should not the tool penetrate the whole
of the way through, the piece may be broken out, and the rough
edges cleaned with a file or a broach.
Fig. 384 is a tool commonly used for drilling the tube-plates for
receiving the tubes of locomotive boilers ; the material is about }
inch thick, and the holes If diameter. The loose cutter a, is fitted
in a transverse mortise, and secured by a wedge ; it admits of being
several times ground, before the notch which guides the blade
for centrality is obliterated. Fig. 385 is somewhat similar to the
last two, but is principally intended for sinking grooves ; and when
the tool is figured as shown by the dotted line, it may be used for
cutting bosses and mouldings on parts of work not otherwise
accessible.
Many ingenious contrivances have been made to insure the
dimensions and angles of tools being exactly retained. In this
class may be placed O'Tool's pin drill, Figs. 386 and 387 ; in action
it resembles the fluted pin drill, Fig. 382, but the iron stock is
Figs. 386
much heavier, and is attached to the drilling machine by the square
tang ; the stock has two grooves at an angle of about 10 degrees
with the axis, and rather deeper behind than in front. Two steel
cutters, or nearly parallel blades represented black, are laid in the
grooves; they are fixed by the ring and two set screws, and
DRILLS. 397
are advanced as they become worn away, by two adjusting screws,
a a, (one only seen), placed at the angle of 10° through the second
ring ; which, for the convenience of construction, is screwed upon
the drill shaft just beyond the square tang whereby it is attached
to the drilling machine. The cutters are ground at the extreme
ends, but they also require an occasional touch on the oilstone, to
restore the keenness of the outer angles, which become somewhat
rounded by the friction. The diminution from the trifling ex-
terior sharpening, is allowed for by the slightly taper form of the
blades.
The process of drilling generally gives rise to more friction
than that of turning, and the same methods of lubrication are
used, but rather more commonly and plentifully ; thus oil is used
for the generality of metals, or from economy, soap and water ;
milk is the most proper for copper, gold, and silver ; and cast-iron
and brass are usually drilled without lubrication. For all the
above-named metals and for alloys of similar degrees of hardness
the common pointed steel drills are generally used ; but for lead
and very soft alloys, the carpenters' spoon bits, and nose bits, are
usually employed, with water.
Having considered the most general forms of the cutting parts
of drills, we will proceed to explain the modes in which they are
put in action by hand-power, beginning with those for the smallest,
diameters, and proceeding gradually to the largest.
METHODS OF WORKING DRILLS BY HAND-POWER. — The smallest
holes are those required in watch- work, and the general form of
the drill is shown on a large scale in Fig. 388 ; it is made of a
piece of steel wire, which is tapered oft' at the one end, flattened with
the hammer, and then filled up in the form shown at large in Fig.
370 ; lastly, it is hardened in the candle. The reverse end of the
instrument is made into a conical point, and is also hardened ; near
this end is attached a little brass sheave for the line of the drill-
bow, which in watchmaking is sometimes a fine horse-hair, stretched
by a piece of whalebone of about the size of a goose's quill
stripped of its feather
Fig. 388.
The watchmaker holds most of his works in the fingers, both
for fear of crushing them with the table vice, and also that he may
the more sensibly feel his operations ; drilling is likewise performed
by him in the same manner. Having passed the bow-string around
the pulley in a single loop (or with a round turn), the centre of the
drill is inserted in one of the small centre holes in the sides of the
table vice, the point of the drill is placed in the mark or cavity
made in the work by the centre punch ; the object is then pressed
398 THE PRACTICAL METAL-WORKEIi's ASSISTANT.
forward with the right hand, whilst the bow is moved with the
left ; the Swiss workmen apply the hands in the reverse order, as
they do in using the turn-bench.
Clockmakers, and artisans in works of similar scale, fix the ob-
ject in the tail- vice, and use drills, such as Fig. 388, but often
larger and longer ; they are pressed forward by the chest, which is
defended from injury by the breast-plate, namely, a piece of wood
or metal about the size of the hand, in the middle of which is a
plate of steel, with centre holes for the drill. The breast-plate is
sometimes strapped round the waist, but is more usually supported
with the left hand, the fingers of which are ready to catch the
drill should it accidentally slip out of the centre.
As the drill gets larger, the bow is proportionally increased in
stiffness, and eventually becomes the half of a solid cone, about 1
inch in diameter at the larger end, and 30 inches long ; the catgut
string is sometimes nearly an eighth of an inch in diameter, or is
replaced by a leather thong. The string is attached to the smaller
end of the bow by a loop and notch, much the same as in the
archery bow, and is passed through a hole at the larger end, and
made fast with a knot ; the surplus length is wound round the
cane, and the cord finally passes through a notch at the end, which
prevents it from uncoiling.
Steel bows are also occasionally used ; these are made something
like a fencing foil, but with a hook at the end for the knot or loop
of the cord, and with a ferrule or a ratchet, around which the spare
cord is wound. Some variations also are made in the sheaves of
the large drills ; sometimes they are cylindrical, with a fillet at
each end ; this is desirable, as the cord necessarily lies on the
sheave at an angle, in fact in the path of a screw; it pursues that
path, and with the reciprocation of the drill-bow, the cord trav-
erses, or screws backwards and forwards upon the sheave, but is
prevented from sliding off by the fillet. Occasionally, indeed,
the cylindrical sheave is cut with a screw coarse enough to receive
the cord, which may then make three or four coils for increased
purchase, and have its natural screw-like run without any fretting
whatever ; but this is only desirable when the holes are large, and
the drill is almost constantly used, as it is tedious to wind on the
cord for each individual hole. The structure of the bows, breast-
plates, and pulleys, although often varied, is sufficiently familiar to
be understood without figures. •
When the shaft of the drill is moderately long, the workman
can readily observe if the drill is square with the work as regards
the horizontal plane ; and to remove the necessity for the observa-
tion of an assistant as to the vertical plane, a trifling weight is
sometimes suspended from the drill shaft by a metal ring or hook ;
the joggling motion shifts the weight to the lower extremity ; the
tool is only horizontal when the weight remains central.
In many cases, the necessity for repeating the shaft and pulley
of the drill is avoided by the employment of holders of various
DRILLS.
399
kinds, or drill-stocks, which serve to carry any required number of
drill points. The most simple of the drill-stocks is shown in Fig.
389 ; it has the centre and pulley of the ordinary drill, but the op-
Figs. 389
390.
posite end is pierced with a nearly cylindrical hole, just at the
inner extremity of which a diametrical notch is filed. The drill is
shown separately at a ; its shank is made cylindrical, or exactly to
fit the hole, and a short portion is nicked down also to the diamet-
rical line so as to slide into the gap in the drill-stock, by which
the drill is prevented from revolving : the end serves also as an
abutment, whereby it may be thrust out with a lever. Sometimes
a diametrical transverse mortise, narrower than the hole, is made
through the drill- stock, and the drill is nicked in on both sides;
and the designer, Mr. R. Balfe, of Kilkenny, proposes that the
cylindrical hole of 389 should be continued to the bottom of the
notch, that the end of the drill should be filed off obliquely, and
that it should be prevented from rotating by a pin inserted through
the cylindrical hole parallel with the notch ; the taper end of the
drill would then wedge fast beneath the pin.
Drills are also frequently used in the drilling-lathe; this is a
miniature lathe-head, the frame of which is fixed in the table vice;
the mandrel is pierced for the drills, and has a pulley for the bow,
therein resembling Fig. 390, except that it is used as a fixture.
The figure 390, just referred to, represents one variety of another
common form of the drill-stock, in which the revolving spindle is
fitted in a handle, so that it may be held in any position without
the necessity for the breast-plate ; the handle is hollowed out to
serve for containing the drills, and is fluted to assist the grasp.
Figs.
391— ~t
392
JK--+-:
44tt L L i 1
4-UW L-J 1 !
b93. -•-'
400 THE PRACTICAL METAL-WORKER's ASSISTANT.
Fig. 391 represents the socket of an "universal drill-stock" in-
vented by James O'Ryan : it is pierced with a hole as large as the
largest of the wires of which the drills are formed, and the hole
terminates in an acute hollow cone. The end of the drill-stock is
tapped with two holes, placed on a diameter; the one screw, a, is of
a very fine thread, and has at the end two shallow diametrical
notches; the other, b, is of a coarser thread, and quite flat at the
extremity. The wire-drill is placed against the bottom of the hole,
and allowed to lean against the adjusting- screw a, and if the drill
be not central, this screw is moved one or several quarter- turns,
until it is adjusted for centrality ; after which the tool is strongly
fixed by the plain set-screw b.
Fig. 392 is a drill-stock contrived by Mr. Murphy. It consists
of a tube, the one end of which has a fixed centre and pulley,
much the same as usual. The opposite end of the tube has a piece
of steel fixed into it which is first drilled with a central hole, and
then turned as a conical screw, to which is fitted a corresponding
screw nut, n ; the socket is then sawn down with two diametrical
notches, to make four internal angles ; and lastly, the socket is
hardened. When the four sections are compressed by the nut,
their edges stick into the drill and retain it fast, and, provided the
instrument is itself concentric, and the four parts are of equal
strength, the centrality of the drill is at once insured. The out-
side of the nut, and the square hole in the key k, are each
taper, for more ready application ; and the drills are of the most
simple kind, namely, lengths of wire pointed at each end, as in
Fig. 393.
The sketch, Fig. 392, is also intended to explain another useful
application of this drill-stock as an upright or pump-drill, well
known among the ancient Irish as the breast-drill. Occasionally
the pump-drill and the common drill-stock are mounted in frames,
by which their paths are more exactly defined ; but these con-
trivances are far from being generally required, and enough will
be said in reference to the use of revolving braces, to lead to such
applications, if considered requisite, for reciprocating drills.
Holes that are too large to be drilled solely by the breast-drill
and drill-bow, are frequently commenced with those useful instru-
ments, and are then enlarged by means of the hand -brace, which
is very similar to that used in carpentry, except that it is more
commonly made of iron instead of wood, is somewhat larger, and
generally made without the spring-catch.
Holes may be extended to about half an inch diameter with
the hand-brace ; but it is much more expeditious to employ still
larger and stronger braces, and to press them into the work in
various ways by weights, levers, and screws, instead of by the
muscular effort alone.
Fig. 394 represents the old smith's press-drill, which although
cumbrous and much less used than formerly, is nevertheless simple
nnd effective. It consists of two pairs of wooden standards, be
DRILLS.
401
tween which works the beam a b, the pin near a is placed at any
height, but the weight w is not usually changed, as the greater or
less pressure for large and small drills is obtained by placing the
brace more or less near to the fulcrum a ; and this part of the beam
is shod with an iron plate full of small centre holes for the brace.
The weight is raised by the second lever c d, the two being united
by a chain, and a light chain or rope is also suspended from d,
to be within reach of the one or two men engaged in moving
the brace. It is necessary to relieve the weight when the drill
is nearly through the hole, otherwise it might suddenly break
through, and the drill becoming fixed, might be twisted off in
the neck.
The inconveniences in this machine are, that the upper point of
the brace moves in an arc instead of a right line ; the limited path
when strong pressures are used, which makes it necessary to shift
the fulcrum a ; and also the necessity for re-adjusting the work
under the drill for each different hole, which in awkwardly-shaped
pieces is often troublesome.
A portable contrivance, of similar date, is an iron bow frame or
clamp, shown in Fig. 395. The pressure is applied by a screw,
but in almost all cases, whilst the one individual drills the hole,
the assistance of another is required to hold the frame ; 395 only
applies to comparatively thin parallel works, and does not present
the necessary choice of position. Another tool of this kind, used
for boring the side holes in cast-iron pipes for water and gas, is
doubtless familiarly known ; the cramp or frame divides into two
branches about two feet apart, and these terminate like hooks,
which loosely embrace the pipe, so that the tool retains its position
without constraint, and it may be used with great facility by one
individual.
Fig. 396 will serve to show the general character of various con-
structions of more modern apparatus, to be used for supplying the
pressure in drilling holes with hand braces. It consists of a cylin-
drical bar a, upon which the horizontal rectangular rod b is fitted
with a socket, so that it may be fixed at any height, or in any
angular position, by the set-screw c. ' Upon b slides a socket; which
26
402
THE PRACTICAL METAL-WORKEIVS ASSISTANT.
Fig. 396.
is fixed at all distances from a by its
set-screw d\ and lastly, this socket has
a long vertical screw e, by which the
brace is thrust into the work.
The object to be drilled having beei;
placed level, either upon the ground,
on trestles, on the work bench, or in
the vice, according to circumstances,
the screws c and d are loosened, and
the brace is put in position for work.
The perpendicularity of the brace is
then examined with a plumb-line, ap-
plied in two positions (the eye being
first directed as it were along the
north and south line, and then along
the east and west), after which the
whole is made fast by the screws c
and d. The one hole having been
drilled, the socket and screws present
great facility in re-adjusting the in-
strument for subsequent holes without
the necessity for shifting the work, which would generally be
attended with more trouble than altering the drill-frame by its
screws.
Sometimes the rod a is rectangular, and extends from the floor
to the ceiling ; it then traverses in fixed sockets, the lower of which
has a set screw for retaining any required position. In the tool
represented, the rod a terminates in a cast-iron base, by which it
may be grasped in the tail- vice, or when required it may be fixed
upon the bench ; in this case the nut a is unscrewed, the cast-iron
plate, when reversed and placed on the bench, serves as a pedestal,
the stem is passed through a hole in the bench, and the nut and
washer, when screwed on the stem beneath, secure all very strongly
together. Even in establishments where the most complete drill-
ing machines driven by power are at hand, modifications of the
press drill are among the indispensable tools : many are contrived
with screws and clamps, by which they are attached directly to
such works as are sufficiently large and massive to serve as a
foundation.
Various useful drilling tools for engineering works are fitted
with left hand screws, the unwinding of which elongate the tools ;
so that for these instruments which supply their own pressure, it is
only necessary to find a solid support for the centre They apply
very readily in drilling holes within boxes and panels,- and the
abutment is often similarly provided by projecting parts of the
castings ; or otherwise the fixed support is derived from the wall
or ceiling, by aid of props arranged in the most Convenient manner
that presents itself.
Fig. 397 is the common brace, whrch only differs from that in
DRILLS.
403
Fig. 396 in the left hand screw ; a right hand screw would be. un-
wound in the act of drilling a hole when the brace is moved round
in the usual direction, which agrees with the path of a left hand
screw. The cutting motion produces no change in the length of
the instrument, and the screw being held at rest for a moment
during the revolution, sets in the cut ; but towards the last, the
feed is discontinued, as the elasticity of the brace and work suffice
for the reduced pressure required when the drill is nearly through,
and sometimes the screw is unwound still more to reduce it.
The lever-drill, Fig. 398, differs from the latter figure in many
respects ; it is much stronger, and applicable to larger holes ; the
drill socket is sufficiently long to be cut into the left hand screw,
and the piece serving as the screwed nut, is a loop terminating in
the centre point. The increased length of the lever gives much
greater purchase than in the crank-formed braxje, and in addition
the lever-brace may be applied close against a surface where the
crank-brace cannot be turned round ; in this case the lever is only
moved a half circle at a time, and is then slid through for a new
purchase, or sometimes a spanner or wrench is applied directly
upon the square drill socket.
Figs. 397
400
The same end is more conveniently fulfilled by the ratchet-drill,
Fig. 399, apparently derived from the last : it is made by cutting
ratchet teeth in the drill shaft, or putting on the rachet as a sepa-
rate piece, and fixing a pall or detent to the handle ; the latter may
then be moved backward to gather up the teeth, and forward to
thrust round the tool, with less delay than the lever in Fig. 398,
and with the same power, the two being of equal length. This
tool is also peculiarly applicable to reaching into angles and places
in which neither the crank-form brace, nor the lever-drill will
apply. Fig. 400, the ratchet-lever, in part resembles the ratchet-
drill, but the pressure-screw of the latter instrument must be
404
THE PRACTICAL METAL-WORKER'S ASSISTANT.
sought in some of the other contrivances referred to, as the rat
chet-lever has simply a square aperture to fit on the tang of the
drill d, which latter must be pressed forward by some independent
means.
Fig. 401, which is a simple but necessary addition to the braces
and drill tools, is a socket having at one end a square hole to re-
ceive the drills, and at the opposite, a square tang to fit the brace ;
by this contrivance the length of the drill can be temporarily ex-
tended for reaching deeply seated holes. The sockets are made
of various lengths, and sometimes two or three are used together,
to extend the length of the brace to suit the position of the prop ;
but it must be remembered that, with the additional length, the
torsion becomes much increased, and the resistance to end-long
pressure much diminished, therefore the sockets should have a bulk
proportionate to their length.
The French brace is also constructed in iron, with a pair of
equal bevel pinion?; and a left hand centre screw, like the tools
Figs. 397, 398, and 399 ; it is then called the comer-drill. Some-
times also, as in Figs. 402 and 403, the bevel wheels are made with
a hollow square or axis, as in the ratchet-lever, Fig. 400 ; the
driver then hangs loosely on the square shank of the drill tool, or
cutter bar, and when the pinion on the handle is only one-third or
fourth of the size of the bevel wheel with the square hole, it is an
effective driver for various uses ; the long tail or lever serves to
prevent the rotation of the driver, by resting against some part of
the work or of the work-bench.
Fig. 402
/TV
Fig. 403.
All the before-mentioned tools are commonly found in a variety
of shapes in the hands of the engineer, but it will be observed they
are all driven by hand power, and are carried to the work. I shall
conclude this section with the description of a more recent drill
tool of the same kind, invented by Mr. O'Kelly of Dublin.
DRILLS.
405
This instrument is represented of one-eighth size, in the side
view, Fig. 404, in the front view, 405, and in the section, 406 ; it is
about twice as powerful as Fig. 403, and has the advantage of feed-
ing the cut by a differential motion. The tangent screw moves at
the same time the two worm wheels a and b ; the former has 15
teeth, and serves to revolve the drill; the latter has 16 teeth, and
by the difference between the two, or the odd tooth, advances the
drill slowly and continually, which may be thus explained.
The lower wheel a, of 15 teeth, is fixed on the drill shaft, and
this is tapped to receive the centre screw c, of four threads per
inch. The upper wheel of 16 teeth is at the end of a socket 'd.
(which is represented black in the section Fig. 406), and is con-
nected with the centre screw c, by a collar and internal key, which
last fits a longitudinal groove cut up the side of the screw c ; now,
therefore, the internal and external screws travel constantly round,
and nearly at the same rate, the difference of one tooth in the
wheels serving continually and slowly to project the screw c, for
feeding the cut. To shorten or lengthen the instrument rapidly,
the side screw e is loosened ; this sets the collar and key free from
the 16 wheel, and the centre screw may for the time be moved in-
dependently by a spanner.
Figs. 404
405
406.
=3=3
The differential screw-drill, having a double thread in the large
worm, shown detached at/, requires 7 J turns of the handle to move
the drill once round, and the feed is one 64th of an inch for each
turn of the drill ; that being the sum of 16 by 4.
DRILLING AND BORING MACHINES. — The motion of the lathe
mandrel is particularly proper for giving action to the various
single-cutting drills referred to ; they are then fixed in square or
round hole drill-chucks which screw upon the lathe mandrel.
The motion of the lathe is more uniform than that of the hand
tools, and the popit-head, with its flat boring flange and pressure
screw, forms a most convenient arrangement, as the works are then
carried to the drill exactly at right angles to the face. But in
drilling very small holes in the lathe, there is some risk of uncon-
sciously employing a greater pressure with the screw than the
406 THE PRACTICAL METAL- WORKER'S ASSISTANT.
slender drills will bear. Sometimes the cylinder is pressed forward
by a horizontal lever fixed on a fulcrum ; at other times the cylin
der is pressed forward by a spring, by a rack and pinion motion,
or by a simple lever, and the best arrangement of this latter kind
is that next to be described.
In the manufacture of harps there is a vast quantity of small
drilling, and the pressure of the cylinder popit-head is given by
means of a long, straight, double ended lever, which moves hori
zontally (at about one-third from the back extremity), upon a
fixed post or fulcrum erected upon the back-board of the lathe.
The front of the lever is connected with the sliding cylinder by a
link or connecting rod, and the back of the lever is pulled towards
the right extremity of the lathe, by a cord which passes over a
pulley at the edge of the back-board, and then supports a weight
of about twenty pounds.
Both the weight and connecting rod may be attached at various
distances from the fixed fulcrum between them. When they are
fixed at equal distances from the axis of the lever, the weight, if
twenty pounds, presses forward the drill with twenty pounds, less
a little friction ; if the weight be two inches from the fulcrum and
the connecting rod eight inches, the effect of the weight is reduced
to five pounds ; if, on the other hand, the weight be at eight and
the connecting rod at two inches, the pressure is fourfold, or eighty
pounds.
The connecting rod is full of holes, so that the lever may be ad-
justed exactly to reach the body of the workman, who standing
with his face to the mandrel, moves the lever with his back, and
has therefore both hands at liberty for managing the work. Some-
times a stop is fixed on the cylinder, for drilling holes to one fixed
depth ; gages are attached to the flange, for drilling numbers of
similar pieces at any fixed distance irom the edge : in fact, this very
useful apparatus admits of many little additions to facilitate the use
of drills and revolving cutters.
Great numbers of circular objects, such as wheels and pulleys,
are chucked to revolve truly upon the lathe mandrel, whilst a sta-
tionary drill is thrust forward against them, by which means the
concentricity between the hole and the edge is insured.
The drills employed for boring works chucked on the lathe, have
mostly long shafts, some parts of which are rectangular or parallel,
so that they may be prevented from revolving by a hook wrench, a
spanner or a hand-vice, applied as a radius, or by other means.
The ends of the drill shafts are pierced with small centre holes, in
order that they may be thrust forward by the screw of the popit-
head, either by hand or by self-acting motion : namely, a connection
between either the mandrel or the prime mover of the lathe, and
the screw of the popit-head, by cords and pulleys, by wheels and
pinions, or other contrivances.
The drills, Figs. 376 and 378, p. 394, are used for boring ordinary
holes : but for those requiring greater accuracy, or a more exact
DRILLS.
407
repetition 'of the same diameter, the lathe drills, Figs. 407 to 409
are commonly selected. Fig. 407, which is drawn in three views
and to the same scale as the former examples, is called the half-
round bit, or the cylinder lit. The extremity is ground a little in-
clined to the right angle, both horizontally and vertically, to about
the extent of three to five degrees. It is necessary to turn out a
shallow recess exactly to the diameter of the end of the bit as a
commencement ; the circular part of the bit fills the hole, and is
thereby retained central, whilst the left angle removes the shaving.
This tool should never be sharpened on its diametrical face, or it
would soon cease to deserve its appellation of half-round bit : some
indeed give it about one-thirtieth more of the circumference. It is
generally made very slightly smaller behind, to lessen the friction ;
and the angle, not intended to cut, is a little blunted half-way round
the curve, that it may not scratch the hole from the pressure of the
cutting edge. It is lubricated with oil for the metals generally,
but is used dry for hard woods and ivory, and sometimes for brass.
The rose-bit, Fig. 408, is also very much used for light finishing
cuts, in brass, iron, and steel ; the extremity is cylindrical, or in the
smallest degree less behind, and the end is cut into teeth like a
countersink ; the rose-bit, when it has plenty of oil, and but very
little to remove, will be found to act beautifully, but this tool is
less fit for cast-iron than the bit next to be described. The rose-bit
may be used without oil for the hard woods and ivory, in which
it makes a very clean hole; but as the end of the tool is chamfered,
it does not leave a flat-bottomed recess the same as the half-round
bit, and is therefore only used for thoroughfare holes.
Figs. 407
408
409
410
411
The drill, Fig. 409, is much employed, but especially for cast-
iron work ; the end of the blade is made very nearly parallel, the
two front corners are ground slightly rounding, and are chamfered,
the chamfer is continued at a reduced angle along the two sides, to
the extent of about two diameters in length : this portion is not
iOS THE PRACTICAL METAL- WORKER'S ASSISTANT.
strictly parallel, hut is very slightly largest in the middle or barrel-
shaped : this drill is us3d dry for cast-iron.
Fig. 409, in common with all drills that cut on the side, may, by
improper direction, cut sideways, making the hole above the in-
tended diameter ; but when the hole has been roughly bored with a
common fluted drill, the end of the latter is used as a turning tool,
to make an accurate chamfer, the bit 409 is then placed through
the stay, as shown in Fig. 410, and is lightly supported between
the chamfer upon the work and the centre of the popit-head ; the
moment any pressure comes on the drill, its opposite edges stick
into the inner sides of the loop (as more clearly explained in Fig.
411), which thus restrains its position; much the same as the point
and edges of the turning tools for iron dig into the rest, and secure
the position of those tools.
It is requisite the drill and loop should be exactly central ; Fig.
410 shows the common form of the stay when fitted to the lathe
restrbut it is sometimes made as a swing gate, to turn aside, whilst,
the piece which has been drilled is removed, and the next piece tr
be operated upon is fixed in the lathe. Sometimes also the drili
409 has blocks of hardwood attached above and below it, to com-
plete the circle ; this is usual for wrought-iron and steel, and oil is
then employed.
These three varieties are exclusively lathe-drills, and are in-
tended for the exact repetition of a number of holes of the par-
ticular sizes of the bits, and which, on that account, should remove
only a thin shaving to save the tools from wear.
The cylinder bits, however, may be used for enlarging holes
below half an inch, to the extent of about one-third their diameter
at one cut ; and for holes from half an inch to one inch, about
one-fourth their diameter or less, and as the bits increase in size,
the proportion of the cut to the diameter should decrease.
The cylinder bit is not intended to be used for drilling holes in
the solid material, and as the piercing drills are apt to swerve in
drilling small and very deep holes, the following rotation in the
tools is sometimes resorted to. A drill, Fig. 376, p. 394, say three-
sixteenths diameter, is first sent into the depth of an inch or up-
wards, and the hole is enlarged by a cylinder bit of one-quarter
inch diameter. The centre at the end of the hole is then restored
to exact truth, by Fig. 380, a re-centering drill, the plug of which
exactly fits the hole made by the cylinder bit ; the extremity of
the re-centering drill then acts as a fixed turning tool, and should
the first drill have run out of its position, Fig. 380 corrects the
centre at the end of the hole. Another short portion is then
drilled with Fig. 376, enlarged with the half-round bit, and the
conical extremity is again corrected with the re-centering drill ;
the three tools are thus used in rotation until the- hole is completed,
and which may be then cleaned out with one continued cut, madt?
with a half-round bit a little larger than that previously used.
Some of the large half-round bits are so made that the one ptocli
DRILLS.
409
will serve for several cutters of different diameters. In the bits
used for boring out ordnance, the parallel shaft of the boring bar
slides accurately in a groove, exactly parallel with the bore of the
gun ; the cutting blade is a small piece of steel affixed to the end
of the half-round block, which is either entirely of iron, or partly
of wood ; and the cut is advanced by a rack and pinion move-
ment, actuated either by the descent of a constant weight, or by a
self-acting motion derived from the prime mover. For making
the spherical, parabolical or other termination to the bore, cutters
of corresponding forms are fixed to the bar.
The outside of the gun is usually turned, whilst the boring is
going on, by hand tools. A plug of copper is screwed into the
brass guns to be perforated for the touch-hole, copper being less
injured by repeated discharges, than the i\lloy of nine parts copper
and one part tin, used for the general substance of the gun ; the
curved bit smooths off' the end of the plug.
There are very many works which from their weight or size,
cannot be drilled in the lathe in its ordinary position, as it is
scarcely possible to support them steadily against the drill ; but
these works are readily pierced in the drilling machine, which may
be viewed as a lathe with a vertical mandrel, and with the flange
of the popit-head, enlarged into a table for the work, which then
lies in the horizontal position simply by gravity, or is occasionally
fixed on the table by screws and clamps. The structure of these
important machines admits of almost endless diversity, and in
nearly every manufactory some peculiarity of construction may be
observed.
Figs. 412 and 413, exhibit a "Portable Hand-drill," which is
introduced as a simple and efficient example, that may serve to
Figs. 412
convey the general characters of the drilling machines. The
spindle is driven by a pair of bevel pinions, the one is attached to
the axis of the vertical fly-wheel, the other to the drill shaft, which
is depressed by a screw moved by a small hand-wheel.
Sometimes, as in the lathe, the drilling spindle revolves without
410
THE PRACTICAL METAL-WORKER'S ASSISTANT.
endlong motion, and the table is raised by a treadle or by a hand
lever ; but more generally the drill-shaft is cylindrical and revolves
in, and also slides through fixed cylindrical bearings. The drill
spindle is then depressed in a variety of ways ; sometimes by a
simple lever, at other times by a treadle, which either lowers the
shaft only one single sweep, or by a ratchet that brings it down by
several small successive steps, through a greater distance ; and
mostly a counterpoise weight restores the parts to their first posi-
tion when the hand or foot is removed. Friction clutches, trains
of differential wheels, and other modes are also used in depressing
the drill spindle, or in elevating the table by self-acting motion.
Frequently also the platform admits of an adjustment independent
of that of the spindle, for the sake of admitting larger pieces ;
the horizontal position of the platform is then retained by a slide,
to which a rack and pinion movement, or an elevating screw is
added.
Drilling machines of these kinds are generally used with the
ordinary piercing drills, and occasionally with pin drills ; the latter
instrument appears to be the type of another class of boring tools,
namely, cutter bars, which are used for works requiring holes of
greater dimensions, or of superior accuracy, than can be attained
by the ordinary pointed drills.
The small application of this principle, or of cutter bars, is shown
on the same scale as the former drills, in Fig. 414 ; the cutter is
placed in a diametrical mortise in a cylindrical boring bar, and is
fixed by a wedge ; the cutter extends equally on both sides, as
the two projections or ears embrace the aides of the bar, which is
slightly flattened near the mortises.
Cutter bars of the same kind are occasionally employed with
cutters of a variety of forms, for making grooves, recesses, mould-
ings, and even screws, upon parts of heavy works, and those which
cannot be conveniently fixed in the ordinary lathe. Fig. 415 repre-
sents one of these, but its application to screws will be found in the
jhapter on the tools for screw cutting.
Figs. 414
416
415
The larger application of this principle is shown in Fig. 415, in
which a cast-iron cutter-block is keyed fast upon a cylindrical bar :
the blqck has four, six, or more grooves in its periphery. Some-
DRILLS. 411
times, the work is done with only one cutter, and should the bar
vibrate, the remainder of the grooves are filled with pieces of hard
wood, so as to complete the bearing at so many points of the circle;
occasionally cutters are placed in all the grooves, and carefully
adjusted to act in succession, that is, the first stands a little nearer
to the axis than the second, and so on throughout, in order that
ea^h may do its share of work; but the last of the series takes only
a light finishing cut, that its keen edge may be the longer pre-
served. In all these cutters, the one face is radial, the other dif-
fers only four or five degrees from the right angle, and the cor-
ners of the tools are slightly rounded.
These cutter bars, like the rest of the drilling and boring machin-
ery, are employed in a great variety of ways, but which resolve
themselves into three principal modes :
First, the cutter bar revolves without endlong motion, in fixed
centres or bearings, in fact, as a spindle in the lathe ; the work is
traversed, or made to pass the revolving cutter in a right line, for
which end the work is often fixed to a traversing slide rest. This
mode requires the bar to measure between the supports, twice the
length of the work to be bored, and the cutter to be in the middle
of the bar ; it is therefore unfit for long objects.
Secondly, the cutter bar revolves, and also slides with endlong
motion, the work being at rest ; the bearings of the bar are then
frequently attached in some temporary manner to the work to be
bored, and are often of wood. Cylinders of forty inches diameter
for steam-engines, have been thus bored, by attaching a cast-iron
cross to each end of the cylinder ; the crosses are bored exactly to
fit the boring bar, one of them carries the driving gear, and the
bar is thrust endlong by means of a screw, moved by a ratchet or
star wheel.
In another common arrangement, the boring bar is mounted in
headstocks, much the same as a traversing mandrel, the work is
fixed to the bearers carrying the headstocks, and the cutter bar is
advanced by a screw. The screw is then moved either by the
hand of the workman ; by a star- wheel, or a ratchet wheel, one
tooth only in each revolution ; or else by a system of differential
wheels, in which the external screw has a wheel say of 50 teeth,
the internal screw a wheel of 51 teeth, and a pair of equal wheels
or pinions drives these two screws continually, so that the ad-
vance of the one-fiftieth of the turn of the screw, or their differ-
ence, is equally divided over each revolution of the cutter bar,
much the same as in the differential motion of the screw drill,
Fig. 404.
This second method only requires the interval between the fixed
bearings of the cutter bar to be as much longer than the work as
the length of the cutter-block ; but the bar itself must have more
than twice the length of the work, and requires to slide through
the supports.
Cutter bars of this kind are likewise used in the lathe ; in the
412 THE PRACTICAL METAL-WORKER'S ASSISTANT.
act of boring, the end of the bar then slides like a piston into the
mandrel. Such bars are commonly applied to the vertical borinir
machines of the larger kinds, which are usually fitted with a dif-
ferential apparatus, for determining the progress of the cut ; the
bar then slides through a collar fixed in the bed of the machine.
In some of the large boring machines either one or two hori-
zontal slides are added, and by their aid series of holes may be
bored in any required arrangement. For instance, the several
holes in the beams, or side levers, and cranks of steam-engines, are
bored exactly perpendicular, in a line, and at any precise distances,
by shifting the work beneath the revolving spindle upon the guide
or railway ; in pieces of other kinds, the work is moved laterally
during the revolution of the cutters, for the formation of elongated
countersinks and grooves.
Thirdly. In the largest applications of this principle, the boring
bar revolves upon fixed bearings without traversing ; and it is
only needful that the boring bar should exceed the length of the
work, by the thickness of the cutter block, of which it has com-
monly several of different diameters. The cutter block, now some-
p. 4J- times ten feet diameter, traverses as a
slide down a huge boring bar, whose
diameter is about thirty inches. There
is a groove and key to couple them
together, and the traverse of the cut-
ter block down the bar is caused by
a side screw, upon the end of which
is a large wheel, that engages in a
small pinion, fixed to the stationary
centre or pedestal of the machine.
With every revolution of the cutter
bar, the great wheel is carried around
the fixed pinion, and supposing these
be as ten to one, the great wheel is moved one-tenth of a turn, and
therefore moves the screw one-tenth of a turn also, and slowly trav-
erses the cutter block.
The contrivance may be viewed as a huge, self-acting, and re-
volving sliding-rest, and the diagram 417 shows that the cutter
bars are equally applicable to portions of circles, such as the D
valves of steam-engines, as well as to the enormous interior of the
cylinder itself.
All th'e preceding boring tools cut almost exclusively upon the
end alone. They are passed entirely through the objects, and
leave each part of their own particular diameter, and therefore
cylindrical ; but I now proceed to describe other boring tools, that
cut only on their sides, go but partly through the work, and leave
its section a counterpart of the instrument. These tools are gen-
erally conical, and serve for the enlargement of holes to sizes
intermediate between the gradations of the drills, and also for the
formation of conical holes, as for valves, stopcocks, and other
DRILLS. 413.
works. The common pointed drill, or its multiplication in the rose
countersink, is the type of the series ; but in general the broaches
have sides which are much more nearly parallel.
BROACHES FOR MAKING TAPER HOLES. — The tools for making
taper holes are much less varied than the drills and boring tools
for cylindrical holes.
423
424
425.
The broaches for metal are made solid, and of various section s ;
as half-round, like Fig. 418 ; the edges are then rectangular, but
more commonly the broaches are polygonal, as in Fig. 419, except
that they have 3, 4, 5, 6, and 8 sides, and their edges measure
respectively 60, 90, 108, 120, and 135 degrees. The four, five, and
six-sided broaches are the most general, and the watchmakers em-
ploy a round broach in which no angle exists, and the tool is
therefore only a burnisher, which compresses the metal and rounds
the hole.
Ordinary broaches are very acute, and Fig. 425 may be consid-
ered to. represent the general angle at which their sides meet,
namely, less than one or two degrees ; the end is usually chamfered
off with as many facets as there are sides, to make a penetrating
point, and the opposite extremity encU in a square tang, or shank,
by which the instrument is worked.
Square broaches, after having been filed up, are sometimes
twisted whilst red-hot ; Fig. 424 shows one of these ; the rectan-
gular section is but little disturbed, although the faces become
slightly concave. The advantage of the tool appears to exist in
its screw form : when it is turned in the direction of the spiral, it
cuts with avidity and requires but little pressure, as it is almost
disposed to dig too forcibly into the metal : when turned the re-
verse way, as in unscrewing, it requires as much or more pressure
than similar broaches not twisted. This instrument, if bent in the
direction of its length, either in the act of twisting or hardening,
does not admit of correction by grinding, like those broaches hav-
ing plane faces. It is not much used, and is almost restricted to
wrought-iron and steel.
Large countersinks that do not terminate in a point, are some-
times made as solid cones ; a groove is then formed up one side,
and deepest towards the base of the cone, for the insertion of a
cutter ; see Fig. 420. As the blade is narrowed by sharpening, it
414 THE PRACTICAL METAL-WORKER'S ASSISTANT.
is set a little forward in the direction of its length, to cause its
edge to continue slightly in advance of the general surface, like
the iron of a plane for cutting metal.
Figure 426 represents the broach, invented by James Kinse-
laugh, of Wicklow, Ireland, in which four detached blades are intro-
duced, for the sake of retaining the cone or angle of the broach
Fig. 428.
with greater facility. The bar or stack has four shallow longitud-
inal grooves, which are nearly radial on the cutting face, and
slightly undercut on the other. The grooves are also rather
deeper behind, and the blades are a-little wedge-form both in sec-
tion and in length, to constitute the cone, and the cutting edges.
In restoring the edges of the blades, they are removed from the
stock, and their angles are then more easily tested : when replaced,
they are set nearer to the point, to compensate for their loss of
thickness.
Broaches are also used for perfecting cylindrical holes, as well
as for making those which are taper. The broaches are then made
almost parallel, or a very little the highest in the middle ; they are
filed, with two or three planes at angles of 90 degrees, as in Figs.
421 or 422. The circular part not being able to cut, serves as a
more certain base or foundation, than when the tool is a complete
polygon ; and the stems are commonly made small enough to pass
entirely through the holes, which then agree very exactly as to
size. Such tools are therefore rather entitled to the name of finish-
ing drills, than broaches.
The size of the parallel broaches is often slightly increased by
placing a piece or two of paper at the convex part. Leather and
thin metal are also used for the same purpose. Gun-barrels are
broached with square broaches, the cutting parts of which are
about eight to ten inches long ; they are packed on the four sides
with slips or spills of wood to complete the circle, as in Fig. 423,
in which the tool is supposed to be at work. The size of the bit
is progressively enlarged by introducing slips of thin paper, piece
by piece, between two of the spills of wood and the broach ; the
paper throws the one angle more towards the centre of the hole,
and causes a corresponding advance in the opposite or the cutting
angle. Sometimes, however, only one spill of wood is employed.
A broach used by the philosophical instrument-makers in finish-
ing the barrels of air-pumps, consisted of a thin plate of steel in-
serted diametrically between two blocks of wood, the whole con-
stituting a cylinder with a scraping edge slightly in advance of the
wood. Slips of paper were also added.
According to the .size of the broaches, they are fixed in handles
DRILLS. 415
like brad-awls ; they are used in the brace, or the tap wrench,
namely, a double-ended lever with square • central holes. Some-
times also broaches are used in the lathe just like drills, and for
large works broaching machines are employed. These are little
more than driving gear terminating in a simple kind of universal
joint to lead the power of the steam-engine to the tool, which is
generally left under the guidance of its own edges, according to
the common principle of the instrument.
In drills and broaches the penetrating angles are commonly more
obtuse than in turning tools ; thus in drills of limited dimensions
the hook-form of the turning tool for iron is inapplicable, and in
the larger examples the permanence of the tool is of more conse-
quence than the increased friction. But on account of the ad-
ditional friction excited by the nearly rectangular edges, it is
commonly necessary to employ a smaller velocity in boring than
in turning corresponding diameters, in order to avoid softening the
tool by the heat generated ; and in the ductile fibrous metals, as
wrought-iron, steel, copper and others, lubrication with oil, water,
etc., becomes more necessary than in turning.
The drills and broaches form together a complete series. First,
the cylinder bit, the pin drills, and others with blunt sides, produce
cylindrical holes by means of cutters at right angles to the axis ;
then the cutter becomes inclined at about 45 degrees, as in the
common piercing drill and cone countersink ; the angle becomes
much less in the common taper broaches ; and finally disappears
in the parallel broaches, by which we again produce the cylin-
'drical hole, but with cutters parallel with the axis of the hole.
Still considering the drills and broaches as one group, the drills
have comparatively thin edges, always less than 90 degrees, yet
they require to be urged forward by a screw or otherwise, the re-
sistance being sustained in the line of their axes. The broaches
have much more obtuse edges, never less than 90, and sometimes
extending to 135 degrees ; and yet the greater force required to
cause the penetration of their obtuse edges into the material is
supplied without any screw, because the pressure in all these varied
tools is at right angles to the cutting edge.
. Thus supposing the sides of the broach extended until they meet
in a point, as in Fig. 425, we shall find the length will very many
times exceed the diameter, and by that number will the force em-
ployed to thrust forward the tool be multiplied, the same as in the
wedge, whether employed in splitting timber or otherwise; and
the broach being confined in a hole, it cannot make its escape, but
acts with lateral pressure, directed radially from each cutting edge ;
and the broach under proper management leaves the holes very
smooth and of true figure.
.416 THE PRACTICAL METAL-WORKERS ASSISTANT.
CHAPTER XXIII.
SCREW-CUTTING TOOLS.
AN elementary idea of the form of the screw, or helix, is ob-
tained by considering it as a continuous circular wedge ; and it is
readily modeled by wrapping a wedge-formed piece of paper
around a cylinder. The edge of the paper then represents the
line of the screw, and which preserves one constant angle to the
axis of the contained cylinder, namely, that of the wedge.
The ordinary wedge, or the diagonal, may be produced by the
composition of two uniform rectilinear motions, which, if equal,
produce the angle of 45°, or if unequal, various angles more or
less acute ; and in an analogous manner, the circular wedge or the
screw may be produced of every angle or coarseness by the com-
position of an uniform circular motion, with an uniform rectilinear
motion. And as either the rectilinear or the circular motion may
be given to the work or to the tool indifferently, there are four
distinct modes of producing screws, and which are all variously
modified in practice.
The screw admits of great diversity. It may possess any diame-
ter ; it may also have any angle — that is, the interval between the
threads may be either coarse or fine, according to the angle of the
wedge or the ratio of the two motions ; and the wedge may be
wound upon the cylinder to the right hand or to the left, so as to
produce either right or left hand screws.
The idea of double, triple, or quadruple screws, will be conveyed
by considering two, three, or four black lines drawn on the uncovered
edge of the wedge-formed paper, or likewise by two, three, or four
strings or wires placed in contact, and coiled as a flat band around
the cylinder, the angle remains unaltered, it is only a multiplication
of the furrows or threads ; and lastly, the screw may have any
section, that is, the section of the worm or thread may be angular,
square, round, or of any arbitrary form. Thus far as to the variety
in screws.
The importance of this mechanical element, the screw, in all
works in the constructive arts, is almost immeasurable. For in-
stance, great numbers of screws are employed merely for connect-
ing together the different parts of which various objects are com-
posed; no other attachment is so compact, powerful, or generally
available ; these binding or attachment screws require, by compari-
son, the least degree of excellence. Other screws are used as regu-
lating screws, for the guidance of the slides and the moving parts
of machinery, for the screws of presses and the like ; these kinds
should possess a much greater degree of excellence than the last.
But the most exact screws that can be produced, are quite essen-
tial to the good performance of the engines employed in the grad-
SCREW-CUTTING TOOLS. 417
nation of right lines and circles, and of astronomical and mathe-
matical instruments; in these delicate micrometrical screws, our
wants ever appear to outstrip the most refined methods of ex-
ecution.
The attempt to collect and describe all the ingenious contriv-
ances which have been devised for the construction of screws,
would be in itself a work of no ordinary labor or extent : I must,
therefore, principally restrict myself to those varied processes now
commonly used in the workshops, for producing with comparative
facility, screws abundantly exact for the great majority of pur-
poses. It has been found rather difficult to arrange these ex-
tremely different processes in tolerable order, but that which seems
to be the natural order has been adopted, thus : —
There appears to be no doubt, but that in the earliest produc-
tion of the apparatus for cutting screws, the external screw was
the first piece made ; this plain circular metal screw was serrated
and thus converted into the tap, or cutting tool, by which internal
screws of corresponding size and form were next produced ; and
one of these hollow screws or dies became in its turn the means of
regenerating, with increased truth and much greater facility, any
number of copies of the original external screw. In these several
stages there is a progressive advance towards perfection, as will be
hereafter adverted to.
These hand processes are mostly used for screws, which are at
least as long, if not longer than their* diameters. The rotatory
and rectilinear guides, and the one or several series of cutting
points, are then usually combined within the tool. This first group
will be considered in the succeeding order : —
On originating screws.
On cutting internal screws, with screw taps.
On cutting external screws, with screw dies.
Subsequent improvements have led to the employment of the
lathe in producing from the above, and in a variety of ways, still
more accurate screws. These methods are sometimes used for
screws which possess only a portion of a turn, at other times for
screws twenty or thirty feet long and upwards. The rotatory
guide is always given by the mandrel, the rectilinear guide is vari-
ously obtained, and the detached screw tool or cutter, may have
one single point, or one series of points which touch the circle at
only one place at a time. This second group will be arranged
thus : —
On cutting screws, in the common lathe by hand.
On cutting screws, in lathes with traversing mandrels.
On cutting screws, in lathes with traversing tools.
It may be further observed that the modes described under these
heads are in general applied to very different purposes, and are
only to a limited extent capable of substitution one for the other ;
it is to be also remarked that it has been considered convenient, in
a great measure to abandon, or rather to modify, the usual dis-
27
418 THE PRACTICAL METAL-WORKER'S ASSISTANT.
tinction between the tools respectively used for wood and for
metal. The eighth and concluding section of this subject describes
some refinements in the production of screws which are not com-
monly practiced, and it is in some measure a sequel to the second
section.
ON ORIGINATING SCREWS. — It appears more than probable, that
in the earliest attempts at making a screw, a sloping piece of paper
was cemented around the iron cylinder ; this oblique line was cut
through with a stout knife or a thin edged file, and was then
gradually enlarged by hand until it gave a rude form of screw.
Doubtless as soon as the application of the lathe was generally
known, the work was mounted between centres, so that the prog-
ress of filing up the groove could be more easily accomplished,
or a pointed turning tool could be employed to assist. Such, in
fact, is one of the modes recommended by Plumier, for cutting the
screw upon a lathe mandrel for receiving the chucks, even in pref-
erence to the use of the die-stocks, which, he urged, were liable
to bend the mandrel in the act of cutting the screw.
Nearly similar modes have been repeatedly used for the pro-
duction of original screws ; one account differing in several re-
spects from the above, is described as having been very success-
fully resorted to above fifty years back, at the Soho works, Birm-
ingham, by a workman of the name of Joe Baggs, before the in-
troduction of the screw-cutting lathe. This is an English account
of an English supposed invention.
The screw was seven feet long, six inches diameter, and of a
square triple thread ; after the screw was accurately turned as a
cylinder, the paper was cut parallel exactly to meet around the
same, and was removed and marked in ink with parallel oblique
lines, representing the margins of the threads ; and having been
replaced on the cylinder, the lines were pricked through with a
centre punch. The paper was again removed, the dots were con-
nected by fine lines cut in with a file, the spaces were then cut out
with a chisel and hammer and smoothed with a file, to a sufficient
extent to serve as a lead or guide.
The partly formed screw was next temporarily suspended in the
centre of a cast-iron tube or box strongly fixed against a horizontal
beam, and melted lead mixed with tin, was poured into the box to
convert it into a guide nut ; it then only remained to complete the
thread by means of cutters fixed against the box or nut, but with
the power of adjustment, in fact in a kind of slide-rest, the screw
being handed round by levers.
Another very simple way of originating screws, and which is
sufficiently accurate for some purposes, is to coil a small wire
around a larger straight wire as a nucleus ; this last is frequently
the same wire the one end of which is to be cut into the screw.
The covering wire, whose diameter is equal to the space required
between the threads of the screw, is wound on close and tight, and
made fast at each end. The coiled screw, being enclosed between
SCREW- CUTTING TOOLS. 419
two pieces of hard wood, indents a hollow or counterpart thread,
sufficient to guide the helical traverse, and a fixed cutter completes
this simple apparatus.
Common screws, for some household purposes, have been made
of tinned iron wire ; two covering wires are rolled on together, the
one being removed leaves a space such as the ordinary hollow of
the thread, and when these screws are dipped in a little melted tin,
the two wires become soldered together.
Other modes have been resorted fo for making original screws,
by indenting a smooth cylinder with a sharp-edged cutter placed
across the same at the required angle, and trusting to the surface
or rolling contact to produce the rotation and traverse of the
cylinder, with the development of the screw. In the most simple
application of this method a deep groove is made along a piece of
board in which a straight wire is buried a little beneath the sur-
face. A second groove is made nearly at right angles across the
first, exactly to fit the cutter, which is just like a table knife, and
is placed at the angle required in the screw. The cutter when
slid over the wire indents it, carries it round, and traverses it end-
ways in the path of a screw. A helical line is thus obtained,
which, by cautious management, may be perfected into a screw
sufficiently good for many purposes.
Mr. Walsh, of Dublin, employed a cutter upon cylinders of
wood, tin, brass, iron, and other materials, mounted to revolve
between centres in a triangular bar lathe ; the knife was hollowed
to fit the cylinder, and fixed at the required angle on a block
adapted to slide upon the bar ; the oblique incision carried the
knife along the revolving cylinder. Some hundreds of screws
were thus made, and their agreement with one another was in many
instances quite remarkable. On the whole he gave the preference
to this mode of originating screws.
The apparatus for originating screws for astronomical and other
purposes is represented in plan in Fig. 427, in side elevation in
Fig. 428, and 429 is the front elevation of the cutter frame alone.
This method is also due to Mr. Walsh. The piece intended for
the screw, namely, a a, Fig. 427, is turned cylindrical, and with two
equal and cylindrical -necks ; it is supported in a metal frame with
two semi-circular bearings, b b, which are fixed on a slide moved
by an adjusting screw c.
The instrument generates original screws perfectly true, of any
number of threads, and right or left handed. In this case, the
stock and cutter are made as in Figs. 427, 428, and 429 ; the back
of the stock is made into the segment of a circle, s ; and the top
of the cutter is continued into an index, t. The cutter is a single
thread, and moves on its edge, v, as a centre. This must fit true,
and the stock fit close to the cutter, to keep it perfectly steady :
u, u, two screws, to adjust and fasten the cutter to any required
angle. The cutter should be rather elliptical, for it is best to fit
well to 'the cylinder at the greatest angle it will be ever used
420
THE PRACTICAL METAL-WORKERS ASSISTANT.
When one turn has been given to the cylinder, Fig. 427, a tooth, w
is put into the cut, and screwed fast. This tooth secures the
lead, and causes every following thread to be a repetition of the
first ; and though it might do without, yet this is a satisfactory
security.
Tn cutting ordinary screws, the dies shown separately in Figs.
430 to 433, the consideration of which is for the present deferred,
takes the place of the oblique cutter in the former figures.
The screw is also originated by traversing the tool in a right
line alongside a plain revolving cylinder. Sometimes the tool has
many points, and is guided by the hand alone ; at other times the
tool has but one single point, and is guided mechanically so as to
proceed, say one inch or one foot in a right line, whilst the cylin-
der makes a definite number of revolutions. The tool is then
traversed either by a wedge placed transversely to the axis, by a
chain or metallic band placed longitudinally, or by another screw
connected in various ways with the screw to be produced, by
wheel-work and other contrivances.
ON CUTTING INTERNAL SCREWS, WITH SCREW TAPS. — The screw
is converted into the tap by the removal of parts of its circumfer-
ence, in order to give to the exposed edges a cutting action ; whilst
the circular parts which remain, serve for the guidance of the in-
strument within the helical groove, or hollow thread, it is required
to form.
SCREW-CUTTING TOOLS.
421
In the most simple and primitive method, four planes were filed
upon the screw, as in Fig. 434, but this exposes very obtuse edges
which can hardly be said to cut, as they form the thread partly by
indenting, and partly by raising or burring up the metal ; and as
such they scarcely produce any effect in cast-iron or other crystal-
line materials. Conceiving, as in Fig. 434, only a very small por-
tion of the circle to remain, the working edges of squared taps,
form angles of (90 -f 45 or) 135 degrees with the circumference,
and the angle is the greater, the more of the circle that remains.
It is better to file only three planes, as in Fig. 435, but the angle
is then as great as 120 degrees even under the most favorable cir-
cumstances.
In taps of the smallest size it is imperative to submit to these
conditions, and to employ the above sections. Sometimes small
intermediate facets or planes are tipped off a little obliquely with
the file, to relieve the surface friction ; this gives the instrument
partly the character of a six or eight sided broach, and improves
the cutting action.
Figs. 434 435
436
437
439.
There appears to be no doubt that, for general purposes, the
most favorable angle for the edges of the screw taps and dies is
the radial line, or an angle of 90 degrees. This condition mani-
festly exists in the half-round tap, Fig. 436. I propose that this
should be made half-round, as it will be found that a tap formed
in this way will cut a full clear thread (even if it may be of a
sharp pitch), without making up any part of it by the burr, as is
almost universally the case when blunt-edged or grooved taps are
used.
It has sometimes been objected to me by persons who had not
seen half-round taps in use, that from their containing less substance
than the common forms do, they must be very liable to be broken
by the strain required to turn them in the work. It is proved,
however, by experience, that the strain in their case is so much
smaller than usual, that there is even less chance of breaking them
than the stouter ones. Workmen are aware that a half-round
opening bit makes a better hole and cuts faster than a five sided
one, and yet that it requires less force to use it.
Fig. 437, in which two-thirds of the circle are allowed to remain,
has been also employed for taps; this, although somewhat less
penetrative than the last, is also less liable to displacement with
the tap wrench. It is much more usual to employ three radial
cutting edges instead of one only; and as in the best forms of taps,
they are only required to cut in the one direction, or when they
422
THE PRACTICAL METAL-WORKER'S ASSISTANT.
are screwed into the nut, ttie other edges are then chamfered to
make room for the shavings ; thereby giving the tap a section
somewhat like that of a ratchet wheel, with either three, four, or
five teeth, as in Figs. 438 and 446.
It is more common, however, either to file up the side of the
tap, or to cut by machinery, three concave or elliptical flutes, as in
439 ; this form sufficiently approximates to the desideratum of the
radial cutting edges, it allows plenty of room for the shavings,
and is easily wiped out. What is of equal or greater importance,
it presents a symmetrical figure, little liable to accident in the
hardening, either of distortion from unequal section, as in Figs.
436 and 437, or of cracking from internal angles as in 437 and 438.
Still, considering alone the transverse section of the tap, it will
be conceived that before any of the substance can be removed from
the hole that is being tapped, the circular part of the instrument
must become embedded into the metal a quantity equal to the
thickness of the shaving; and in this respect Figs. 434 and 435, in
which the circular parts are each only the tenth or twelfth of 'the
circumference, appear to have the advantage over the modern taps
438 and 439, in which each arc is twice as long. Such, however,
is not the case, as the first two act more in the manner of the
broach, if we conceive that instrument to have serrated edges ; but
Figs. 438 and 439 act nearly as turning tools, as in general the
outer or the circular surface is slightly relieved with a file, so as
to leave the cutting edges a, somewhat in advance of the general
periphery ; which is equivalent to chamfering the lower plane of
the turning tool some three degrees to produce that relief which
has been appropriately named the angle of separation.
But in the tap Fig. 440, invented by F. O'Neal, this is still more
Figs. 440
441
442
443.
effectually accomplished. The instrument, instead of being turned
of the ordinary circular section in the lathe (or as the outer dotted
line), is turned with three slight undulations, by- means of an alter-
nating radial motion given to the tool. From this it results that,
when the summits of these hills are converted into the cutting
edges, that not only are the extreme edges or points of the teeth
SCREW-CUTTING TOOLS. 423
>r\acle prominent, but the entire serrated surface becomes inclined at
about the three degrees to the external circle, or the line of work,
so as exactly to assimilate to the turning tool ; and therefore there
is little doubt but that, under equal circumstances, O'Neal's tap
would work with less friction than any other.
The principle of chamfering, or relieving the taps, must not,
however, be carried to excess, or it will lead to mischief. For ex-
ample, the tap, if sloped behind the teeth as is Fig. 441, would be
much exposed to fracture ; and the instrument being entirely under
its own guidance, the three series of keen points would be apt to
stick irregularly into the metal, and would not produce the smooth,
circular, or helical hole, obtained when the tool, Fig. 442, is used.
The relief should be slight, and the surfaces of the teeth then
assimilate to the condition of the graver for copper plates, and
thereby direct the tap in a very superior manner.
The teeth sloped in front, as in Fig. 443, would certainly cut
more keenly than those of 442, but they would be much more ex-
posed to accident, as the least backward motion or violence would
be liable to snip off the keen points of the teeth ; and therefore, on
the score of general economy and usefulness, the radial and slightly
relieved teeth of Fig. 442, or rather of 439, are proper for work-
ing taps.
It appears further to be quite impolitic, entirely to expunge the
surface-bearing, or squeeze, from the taps and dies, when these are
applied to the ductile metals ; as not only does it, when slight,
greatly assist in the more perfect guidance of the instrument, but
it also serves somewhat to condense or compress the metal.
Unless the taps cut very freely, it is the general aim to avoid
the necessity for tapping cast-iron, which is a granular and crystal-
line substance, apt to crumble away in the tapping, or in the after
use. The general remedy is the employment of bolts and nuts
made of wrought-iron, or fixing screwed wrought-iron pins in the
work, by means of transverse keys and other contrivances, and
sometimes by the insertion of plugs of gun-metal, to be afterwards
tapped with the screw-threads. In general also, the small screws
for cast-iron are coarse and shallow in the thread compared with
those for wrought-iron, steel, and brass.
The transverse sections hitherto referred to, are always used for
those taps employed in screwing the inner surfaces of the nuts, and
holes required in general mechanism. The longitudinal section of
the working tap is taper and somewhat like a broach, the one end
being small enough in external diameter to enter the blank hole to
be screwed, and the other end being as large as the screw for which
the nut is intended.
In many cases a series of two, three, or four taps must be used
instead of only one single conical tap, and the modifications in
their construction are explained by the following diagrams ; namely,
Fig. 444, the tap formerly used for nuts and thoroughfare holes,
and Fig. 445, the modern tap for the same purposes : the dotted
lines in each represent the bottoms of the threads.
424
THE PKACTICAL METAL-WORKER'S ASSISTANT.
In the former kind, the thread was frequently finished of a taper
figure, with the screw tool in the lathe ; after which either the four
or three plane surfaces were filed upon it, as shown by the section
at s ; the neck from ftog was as small as the bottom of the thread,
and the tang from g to h was either square or rectangular for the
tap wrench. The tang, if square, was also taper, the tap wrench
then wedged fast upon the tap ; the sides of the tang, if parallel,
were rectangular, and measured as about one to two, and there
were shoulders on two sides to sustain the wrench.
Fig. 444.
'iN i !
i 5
c b
I i I
ed f
Fig. 445.
In the modern thoroughfare taps for nuts, drawn to the same
scale in Fig. 445, the thread is left cylindrical, from the screw tool
or the dies ; then from a to b, or about one diameter in length, is
turned down cylindrical until the thread is nearly obliterated ;
from d to / also nearly one diameter in length at the other end, is
left of the full size of the bolt, and the intermediate part, b to d,
equal to three or four diameters, is turned to a cone, after which
the tap is fluted as seen at s. The neck f g, as before, is as small
as the bottom of the thread, and the square g h, measures diagon-
ally the same as the turned neck.
In using the modern instrument, Fig. 445, the hole to be tapped
is bored out exactly to fit the cylindrical plug a b, which therefore
guides the tap very perfectly in the commencement ; the tool is
simply passed once through the nut without any retrograde motion
whatever, and the cylindrical part d /, takes up the guidance when
the larger end of the cone enters the hole ; at the completion, the
tap drops through, the head being smaller than the bottom of the
thread. The old four square taps could not be thus used, for as
they rather squeezed than cut, they had much more friction ; it
was necessary to move them backwards and forwards, and to make
the square for the wrench larger^ to avoid the risk of twisting off'
the head of the tap. In taps of modern construction of less than
half an inch diameter, it is also needful to make the squares larger
than the proportion employed in Fig. 445.
In tapping shallow holes, as only a small portion of the end of
SCREW-CUTTING TOOLS. 425
the tap can be used, the screwed part seldom exceeds two diame-
ters in length, and as they will not take hold when made too coni-
cal, a succession of three or four taps is generally required. The
screwed part of the first may be considered to extend from a to b
of Fig. 444, of the second, from c to d, of the third from e to /;
so that the prior tap may, in each case, prepare for the reception
of the following one. The taps are generally made in sets of
three ; the first, which is also called the entering or taper tap, is in
most cases regularly taper throughout its length ; the second, or
the middle tap, is sometimes taper, but more generally cylindrical,
with just two or three threads at the end tapered off; the third
tap, which is also called the plug or finishing tap, is always cylin-
drical, except at the two or three first threads, which are slightly
reduced.
Taps are used in various ways, according to the degree of
strength required to move them. The smallest taps should have
considerable length, and should be fixed exactly in the axis of
straight handles ; the length serves as an index by which the true
position of the instrument can be verified in the course of work ;
with the same view as to observation, and as an expeditious mode,
taps of a somewhat larger size are driven round by a hand brace,
whilst the work is fixed in the vice. Still larger taps require tap
wrenches, or levers with central holes to fit the square ends of the
taps ; for screw taps from one to two inches diameter, the wrenches
have assumed the lengths of from four to eight feet, although the
recent improvements in the taps have reduced the lengths of the
wrenches to one-half.
Notwithstanding that the hole to be tapped may have been
drilled straight, the tap may by improper direction proceed ob-
liquely ; the progress of the operation should be therefore watched,
and unless the eye serve readily for detecting any falseness of
position, a square should be laid upon the work, and its edge com-
pared with the axis of the tap in two positions.
In tapping deeply seated holes, the taps are temporarily length-
ened by sockets, frequently the same as those used in drilling,
which are represented in Fig. 401, page 403 ; the tap wrench can
then surmount those parts of the work which would otherwise
prevent its application.
Sometimes for tapping two distant holes exactly in one line, the
ordinary taper tap, Fig. 445, is made with the small cylindrical
part a b exceedingly long, so as to reach from the one hole to the
other and serve as a guide or director. This is only an extension
of the short plug a b, Fig. 445, which it is desirable to leave on
most taps used for thoroughfare holes.
Some works are tapped whilst they are chucked on the lathe
mandrel ; in this case the shank of the tap, if in false position,
will swing round in a circle whilst the mandrel revolves, instead
of continuing quietly in the axis of the lathe. Sometimes the centre
point of the popit-head is placed in the centre hole in the head of
426 THE PRACTICAL METAL-WORKER 's ASSISTANT.
the tap ; in those which are fixed in handles it is better the handle
of the tap should be drilled up to receive the cylinder of the popit-
head, as in the lathe taps for making chucks ; this retains the guid-
ance more easily.
Taps of large size, as well as the generality of cutting instru-
ments, have been constructed with detached cutters. For those
exceeding about 1J inch diameter, two steel plugs a a, may be in-
serted within taper holes in the body of the tap, as represented in
Fig. 446, and in the two sections b and c ; the whole is then screwed
and hardened.
Fig. 446.
The advance of the cutters slightly beyond the general line of
the thread, is caused by placing a piece of paper within the mor-
tises a b, and to relieve the surface friction, each alternate tooth in
the middle part of the length of the tap is filed away. Sometimes
the cutters are parallel and inserted only partway through, and are
then projected by set screws placed also on the diameter, as in the
section c.
The cutter bar, Fig. 415, p. 410, may also be viewed as a tap
with detached cutters. The cylindrical bar is supported in tem-
porary fixed bearings, one of which embraces the thread (some-
times by having melted load poured around the same), the bar
moves therefore in the path of a screw. In cutting the external
thread, the cutter represented is shifted inwards with the progress
of the work ; or a straight cutter shifted outwards, serves for mak-
ing an internal screw ; pointed instead of serrated cutters may be
also used; they are frequently adjusted by a set screw instead of
the hammer, and are worked by a wrench.
This screw cutter bar, independently of its use for large awk-
ward works, is also employed for cutting, in their respective situa-
tions, screws required to be exactly in a line with holes or fixed
bearings, as the nuts of slides, presses, and similar works.
Some taps or cutters are made cylindrical, and are used for cut-
ting narrow pieces and edges, such as screw-cutting dies, screw
tools, and worm wheels ; therefore it is necessary to leave much
more of the circle standing, and to make the notches narrower
than the width of the smallest pieces to be cut. But the grooves
should still possess radial sides, and when these are connected by
a curved line, as in Fig. 447, there is less risk of accident in the
hardening. The number of the notches increases with the diame-
ter, but the annexed figure would be better proportioned if it had
SCREW-CUTTING TOOLS. 427
one or two less notches, as inadvertently the teeth have been
drawn too weak.
When the tool, Figs. 447 and 448, is used for cutting the dies of
die stocks it is called an original lap, of which further particulars
Figs. 447 448.
will be given in the succeeding section ; the tool is then fixed in the
vice, and the die-stock is handed round, as in cutting an ordinary
screw. When Fig. 448 is used for cutting up screw tools, or the
chasing-tools for the use of the turning lathe, the cutter is then
called a hob, or a screw-tool cutter, and its diameter is usually
greater; it is now mounted to revolve in the lathe, and the screw
tool to be cut is laid on the rest as in the process of turning, and is
pressed forcibly against the cutter. Another method is proposed :
the inside screw tool is laid in a lateral groove in a cylindrical piece
of iron, and the tool and cylinder are cut up with the die-stocks as
a common screw ; by which mode the inside screw tool obviously
becomes the exact counterpart of the hollow thread of that particular
diameter.
Fig. 448 is also used as a worm-wheel cutter, that is, for cutting
or for finishing the hollow screw-form teeth, of those wheels which
are moved by a tangent screw ; as in the dividing-engine for cir-
cular lines, and many other cases in ordinary mechanism. The
worm-wheel cutter is frequently set to revolve in the lathe, and the
wheel is mounted on a temporary axis so as to admit of its being
carried round horizontally by the cutter ; sometimes the wheel and
cutter are connected by gear.
The contact of the ordinary tangent screw with the worm-wheel,
resembles that of the tangent to the circle, whence the name ; but
Hindley, of York, made the screw of his dividing engine to touch
15 threads of the wheel perfectly, by giving the screw a curved
section derived from the edge of the wheel, and smallest in the
middle.
In cutting the metal screw, or the bolt, the tools are required to
be the converse of the tap, as they must have internal instead of
external threads, but the radial notches are essential alike in each.
For small works, the internal threads are made of fixed sizes and
in thin plates of steel; such are called screw plates; for larger works,
the internal threads are cut upon the edges of two or three detached
pieces of steel, called dies ; these are fitted into grooves within die-
stocks, and various other contrivances which admit of the approach
428 THE PRACTICAL METAL-WORKERS ASSISTANT.
of the screwed dies, so that they may be applied to the decreasing
diameter of the screw, from its commencement to the completion.
The thickness of the screw plate is in general from about two-
thirds to the full diameter of the screw, and mostly several holes
are made in the same plate ; from two to six holes are intended for
one thread, and are accordingly distinguished into separate groups
by little marks, as in Fig. 449. The serrating of the edges is some-
times done by making two or three small holes and connecting
them by the lateral cuts of a thin saw, as in Fig. 450. The notches
alone are sometimes made, and when the holes are arranged as in
Fig. 451, should the screw be broken short off by accident, it may
be cut in two with a thin saw, and thus removed from the plate.
In making small screws, the wire is fixed in the hand- vice, tap-
ered off with a file, and generally filed to an obtuse point ; then,
after being moistened with oil, it is screwed into the one or several
holes in the screw plate, which is held in the left hand. At other
times, the work fixed in the lathe is turned or filed into form, and
the plate is held in the right hand ; but the force then applied is
less easily appreciated. The harp-makers and some others, attach
a screw plate with a single hole to the sliding cylinder of the popit-
head.
Figs. 449 450 451.
The screw plate is sometimes used for common screws as large
as from half to three-quarters of an inch diameter ; such screws are
fixed in the tail vice, and the screw plate is made from about 15 to
80 inches long, and with two handles ; the holes are then made of
different diameters, by means of a taper tap, so as to form the thread
by two, three, or more successive cuts, and the screw should be
entered from the large side of the taper hole. It is, however, very
advisable to use the diestocks, in preference to the screw plates, for
all screws exceeding about one- sixteenth of an inch diameter,
although the unvarying diameter of the screw plate has the advan-
tage of regulating the equal size of a number of screws, and as
such, is occasionally used to follow the diestocks, by way of a gage
for size.
The diestock, in common with other general tools, has received
a great many modifications that it would be useless to trace in
greater detail, than so far as respects the varieties in common use,
or those which introduce any peculiarity of action in the cutting
edges. A notion of the early contrivances for cutting metal screws
SCREW-CUTTING TOOLS.
429
will be gathered from the figures 452 to 455, which are copied
half-size from " Leupold's Theatrum Machinarum Generale. 1724."
For instance, Fig. 452 is the screw plate in two, and jointed i >
gether like a common rule ; the inner edges are cut with threads,
the larger of which is judiciously placed near the joint, that it may
be more forcibly compressed ; there is a guide a, a, to prevent the
lateral displacement of the edges, which would be fatal to the action.
Similar instruments are still used, but more generally for screws
made in the turning lathe.
Figs. 452
453
454
455.
In one of these tools, the frame or stock is made exactly like a
pair of flat pliers, but with loose dies cut for either one or two sizes
of threads. Plier diestocks are also made in the form of common
nut-crackers, or in fact, much like Fig. 452, if we consider it to
have handles proceeding from a a, to extend the tool to about two
or three times its length ; the guide a a is retained, and removable
dies are added, instead of the threads being cut in the sides of the
instrument.
In general, however, the two dies are closed together in a straight
line, instead of the arc of a circle : one primitive method, Fig. 455,
extracted from the work referred to, has been thus remodeled : the
dies are inserted in rectangular tapei holes, in the ends of two long
levers, which latter are connected by two cylindrical pins, care-
fully fitted into holes made through the levers, and the ends of the
pins are screwed aud provided with nuts, which serve more effect-
ually to compress the dies than the square rings represented in
Fig. 455.
The diestock in its most general form has a central rectangular
aperture, within which the dies are fitted, so as 'to admit of compres-
sion by one central, screw ; the kinds most in use being distin-
guished as the double chamfered diestocks, Figs. 456 and 457 ; and the
single chamfered diestock, Figs. 459 and 460, the handles of which
are partly shown by dotted lines. In the former, the aperture is
about as long as three of the dies ; about one-third of the length of
the chamfer is filed away at the end, for the removal of the dies
430
THE PRACTICAL METAL-WORKER'S ASSISTANT.
laterally, and one at a time. In the single chamfered diestock 460,
which is preferable for large threads, the aperture but little exceeds
the length of two dies, and these are removed by first taking off the
side plate b a, which is either attached by its chamfered edges as a
elide, or else by four screws ; these, when loosened, allow the plate
to be slid endways, and it will be then disengaged, as the screws
will leave the grooves at «, and the screw heads will pass through
the holes at b.
458
459
462
460 6 a
Sometimes dies of the section of Fig. 458 are applied after the
manner of 457, and occasionally the rectangular aperture of Fig.
460 is made parallel on its inner edges, and without the side plate
b a ; the dies are then retained by steel plates either riveted or
screwed to the diestock, as represented in Fig. 461, or else by two
steel pins buried half-way in the sides of the stock, and the re-
maining half in the die, as shown in Fig. 462. These variations
are of little moment, as are also those concerning the general form
of the stock : for instance, whether or not the handles proceed in
the directions shown (the one handle being occasionally a con-
tinuation of the pressure screw), or whether the handles are placed
as in the dotted position t. In small diestocks, a short stud or
handle is occasionally attached at right angles to the extremity,
that the diestock may be moved like a winch handle ; and some-
times graduations are made upon the pressure screw, to denote the
extent to which the dies are closed. These and other differences
are matters comparatively unimportant, as the accurate fitting of
the dies, and their exact forms, should receive the principal atten-
tion.
In general only two dies are used, the inner surface of each of
/
'^v,. J^
f f s
SCREW-CUTTING TOOLS. | > 4$f*V
' y
which includes from the third to nearly the half of a circle, and a
notch is made at the central part of each die, so that the pair of
dies present four arcs, and eight series of cutting points or edges ;
four of which operate when the dies are moved in the one direc-
tion, and the other four when the motion is reversed ; that is when
the curves of the die and screw are alike.
The formation of these parts has given rise to much investigation
and experiment, as the two principal points aimed at require di-
rectly opposite circumstances. For instance, the narrower the edges
of the dies, or the less of the circle they contain, the more easily
they penetrate, the more quickly they cut, and the less they com-
press the screw by surface friction or squeezing, which last tends
to elongate the screw beyond its assigned length. Bat, on the
other hand, the broader the edges of the dies, or the more of the
circle they contain, the more exactly do they retain the true helical
form and the general truth of the screw.
The action of screw-cutting dies is rendered still more difficult,
because in general one pair of dies, the curvatures and angles of
which admit of no change, are employed in the production of a
screw, the dimensions of which during its gradual transit from the
smooth cylinder to the finished screw continually change.
For instance, the thread of a screw necessarily passes two mag-
nitudes, namely, the top and bottom of the groove, and also two
angles at these respective diameters, as represented by the dotted
lines in the diagrams, Figs. 463, 465, and 467 (which are drawn
•with straight instead of curved lines). The angles are nearly in
the inverse proportion of the diameters ; or if the bottom were
half the diameter of the top of the thread, the angle at the bottom
would be nearly twice that at the top.
The figures show the original taps, master taps, or cutters, from
which the dies, Figs. 464, 466, and 468, are respectively made ;
and in each of the three diagrams the dies a are supposed to be in
the act of commencing, and the dies b in finishing, a screw of the
same diameter throughout as that in Fig. 463.
Of course the circumstances become the more perplexing the
greater the depth of the thread, whereas in shallow threads the
interference may be safely overlooked. As the dies cannot have
both diameters of the screw, it becomes needful to adopt that cur-
vature which is least open to objection. If, as in Fig. 464, the
curved edges of the dies a and b have the same radii as the finished
screw, in the commencement, or at a, the die will only touch at the
corners, and the curved edges being almost or quite out of contact,
there will be scarcely any guidance from which to get the lead or
first direction of the helix, and the dies will be likely to cut false
screws, or else parallel grooves or rings. In addition to this, the
curved edges present, at the commencement, a greater angle than
that proper for the top of the screw ; but at the completion of the
screw, or at b, the die and screw will be exact counterparts, and
will be therefore perfectly suitable to each other.
432
THE PRACTICAL METAL-WORKERS ASSISTANT.
If, as in Fig. 468, the inner curvature of the dies a and b be the
same as in the blank cylinder, a will exactly agree both in diame-
Figs. 463
«MALL MASTER TAP.
Same diameter at Screw.
II
465
MEDIUM MASTER TAP.
One depth, larger than Screw.
467
LARGE MASTER TAP.
Two depths larger than Screw.
464
468.
ter and angle at the commencement of the screw, but at the con-
clusion, or as at b, each will be too great, and the die and screw will
be far from counterparts, and therefore ill adapted to each other.
The most proper way of solving the difficulty in dies made in
two parts, is by having two pairs of dies, such as 468 and 464
and which is occasionally done in very deep threads, see Figs. 432
and 433. But it is more usual to pursue a medium course, and to
make the original tap or cutter, Fig. 465, used in cutting the dies,
not of the same diameter as the bolt, as in Figs. 463 and 464, not
to exceed the diameter of the bolt by twice the depth of the thread,
as in Figs. 467 and 468, but with only one depth beyond the exact
size, or half-way between the extremes as in Figs. 465 and 466, in
which latter it is seen the contact, although not quite perfect either
at a or b} is sufficiently near at each for general practice.
The obvious effect of different diameters between the die and
screw must be a falsity of contact between the surfaces and angles
of the dies ; thus in 464 the whole of the cutting falls upon e, the
external angles, until the completion of the screw in b, when the
action is rather compressed than cutting. In Fig. 468 the first act
is that of compressing, and all the work is soon thrown on it the
internal angles of the die, which become gradually more pene-
trative, but eventually too much so, being in all respects the reverse
of the former. In the medium and most common example, Fig.
466, the cut falls at first upon the external angles e, it gradually
dies away, and it is during the brief transition of the cut from the
external to the internal angles i, that is, when tfye screw is exactly
half-formed, that the compression principally occurs.
The compression or squeezing is apt to enlarge the diameter of
the screw (literally by swaging up the metal), and also to elongate
SCKEW-CUTTING TOOLS.
433
it beyond its assigned length, and that unequally at different parts.
Sometimes the compression of the dies makes the screw so much
coarser than its intended pitch that the screw refuses.to pass through
a deep hole cut with the appropriate tap. Not only may the total
increase in length be occasionally detected by a common rule, but
the differences between twenty or thirty threads, measured at va-
rious parts with fine-pointed compasses, are often plainly visible.
Other and vastly superior modes for the formation of long screws,
or those requiring any very exact number of threads in each inch
or foot of their length, will be shortly explained. . Yet notwith-
standing the interferences which deprive the diestocks of the
refined perfection of these other methods, they are a most invalu-
able and proper instrument for their intended use ; and the dis-
agreement of curvature and angle is more or less remedied in prac-
tice, by reducing the circular part of the dies in various ways; and
also in some instances, by the partial separation of the guiding from
the cutting action.
The most usual form of dies is shown in Fig. 469, but if every
measure be taken at the mean, as in Fig. 470, the tool possesses a
fair, average, serviceable quality ; that is, the dies should be cut
over an original tap of medium dimensions, namely one depth
larger* than the screw, such as Fig. 465 ; the curved surface should
be halved, making the spaces and curves as nearly equal as may
be; and the edges should be radial. Fig. 471, nearly transcribed
from Leupold's figure, 453, has been also used, but it appears as if
too much of the curve were then removed.
Sometimes the one die is only used for guiding, and the other
only for cutting: thus a, Fig. 472, is cut over two different diameters
of master taps, which gives it an elliptical form. A large master
tap, Fig. 467, is first used for cutting the pair of dies ; this leaves
the large parts of the curve in a ; the dies are subsequently cut
over a small master tap, 463.
Figs. 469 470
471
472
473,
In beginning the screw, the die a, serves as a bed with guiding
edges ; these indent without cutting, and also agree at the first
start, with the full diameter of the bolt ; with the gradual reduc-
tion of the bolt, it sinks down to the bottom of a, which continually
presents an angular ridge, nearly agreeing in diameter, and there-
fore in angle with the nascent screw. The inconveniences of the
dies, Fig. 472, are, that they require a large and a small master tap
28
434
THE PRACTICAL METAL-WORKER'S ASSISTANT.
for the formation of every different sized pair of dies, and which
latter are rather troublesome to repair. The dies also present more
friction than most others, apparently from the screw becoming
wedged within the angular sides of the die a.
In Fig. 473, the dies are first cut over a small master tap, Fig.
464, the threads are then partially filed or turned out of b, to fit the
blank cylinder ; which therefore rests at the commencement upon
blunt triangular, curved surfaces, instead of upon keen edges ; and
as the screw is cut up, its thread gradually descends into the por-
tions of the thread in b, which are not obliterated. About one-
third of the thread is turned out from each side of the cutting die
a, leaving only two or three threads in the centre, as shown in the
last view ; and the surface of this die is left flat, that it may be
ground up afresh when blunted, and which is also done with other
dies having plane surfaces.
Mr. William Eyan and Mr. Patrick Mullen have each proposed
to assist the action of dies for large screws, by means of cutters ;
their plans will be sufficiently explained by the diagrams, Figs.
474 and 475. This mode to large screws of square threads was
applied for gun carriages ; the dies were cut very shallow, say one-
third of the full depth, and they were serrated on their inner faces
to act like saws or files. The dies were used to cut up the com-
mencement of the thread, but when it filled the shallow dies,
their future office was not to cut, but only to guide the ascent and
descent of the stocks, by the smooth surfaces of the dies rubbing
upon the top of the square thread. The remaining portion of the
screw was afterwards ploughed out by a cutter like a turning tool,
the cutter being inserted in a hole in the one die, and advanced
by a set screw, somewhat after the manner represented in the
figures 474 and 475.
Figs. 474
478
475
477
479.
Mullen employed a similar method for angular thread screws,
and the cutter was placed within a small frame fixed to the one
die. The screw bolt was commenced with the pair of dies which
were closed by the set screw a, 474, the cutter being then out
SCREW-CUTTING TOOLS.
435
of action. When the cutter was set to work by its adjusting
screw b, it was advanced a little beyond the face of the die. and
not afterwards moved ; but the advance of a closed the dies upon
the decreasing diameter of the screw, the cutter always continuing
prominent and doing the principal share of the work.
Figure 476 is the plan, and 477 the side elevation, of an old
although imperfect expedient, for producing a left-handed screw
from a right-handed tap. It will be remembered the right and
left-hand screws only differ in the direction of the angle, the thread
of the one coils to the right, of the other to the left hand ; and on
comparing a corresponding tap and die, the inclinations of the ex-
ternal curve of the one, and the internal curve of the other neces-
sarily differ in like manner as to direction. The mode employed,
therefore, is to carry a right-hand tap around the screw to be cut ;
the temporary screw-cutter possesses the same interval or thread as
before, but the cutting angles of the tap, having the reverse direc-
tion of those of the die, the screw becomes left-handed.
The one die in 476 and 477 is merely a blank piece of brass or
iron without any grooves, the other is a brass die in which the tap
is fixed ; as may be expected, the thread produced is not very per-
fect, but in the absence of better means, this mode is available as
the germ for the production of a set of left-hand taps and dies.
Figs. 478 and 479 represent a different mode of originating a left-
handed screw, proposed by Mr. Walsh ; the tool is to be a small
piece of a right-handed screw, which is hardened and mounted in
a frame like an ordinary milling or nurling tool, and intended to
act by pressure alone ; the diameter of the tool and cylinder should
be alike.
The screw stock represented in Fig. 480: three narrow dies
Figs. 480
481
482.
were fitted in three equidistant radial grooves in the stock, the
ends of the dies came in contact with an exterior ring, having on
its inner edge three spiral curves (equivalent to three inclined
planes), and on its outer surface a series of teeth into which worked
436 THE PRACTICAL METAL -WORKER'S ASSISTANT.
a tangent screw, so that on turning the ring by the screw, the
three dies were simultaneously and equally advanced towards the
centre.
These screw stocks were found to cut very rapidly, as every cir-
cumstance was favorable to that action. For instance, on the
principle of the triangular bearing, all the three dies were con-
stantly at work ; the original tap being slightly taper, every thread
in the length of the die was performing its part of the work, the
same as in a taper tap, every thread of which removes its shaving
or share of the material ; and the dies were narrow, with radial
edges, which admitted of being easily sharpened.
The diestock has been abandoned in favor of the screw stock,
which is represented in Fig. 481. The one die embraces about
one- third of the circle, the two others much less; the latter are
fitted into grooves which are not radial, but lead into a point sit-
uated near the circumference of the screw-bolt ; the edges of the
dies are slightly hooked or ground respectively within the radius,
and they are simultaneously advanced by the double wedge and
nut ; the dies are cut over a large original, such as Fig. 467, that
is, two depths larger than the screw. The large die serves to line
out or commence the screw, and the two others act alternately ; the
one whilst the stock descends down the bolt, the other during its
ascent.
We will notice but one more screw stock. It is seen that the
one die embraces about one-third the screw, the other is very nar-
row ; the peculiarity of this construction is that a circular recess
is first turned out of the screw stock, and a parallel groove is made
into the same, the one handle of the stock (which is shaded), nearly
fills this recess, and receives the small die. If the handle fitted
mathematically true, it is clear it would be immovable, but the
straight part of the handle if narrower than the width of the
groove ; when the stock is turned round, say in the direction from
2 to 1, the first process is to rotate the handle in the circle, and to
bring it in hard contact with the side 1, this slightly rotates the
die also, and the one corner becomes somewhat more prominent
than the other. When the motion of the stock is reversed, the
handle leaves the side 1, of the groove, and strikes against the
other side 2, and then the opposite angle of the die becomes the
more prominent ; and that without any thought or adjustment on
the part of the workman, as the play of the handle in the groove
1, 2, is exactly proportioned to cause the required angular change
in the die.
The cutting edges of the die act exactly like turning tools, and
therefore they may very safely be beveled or hooked as such ; as
when they are not cutting, they are removed a little way out of
contact, and therefore out of danger of being snipped off, or of
being blunted by hard friction. The opposite die affords during the
time an efficient guidance for the screw, and the broad die is ad-
vanced in the usual manner, by the pressure screw made in con-
SCKEW-CUTTING TOOLS.
437
tinuation of the second handle of the diestock ; the dies are kept
in their places by a side plate, which is fitted in a chamfered
groove in the ordinary manner.
There is less variety of method in cutting external screws with
the diestocks, than internal screws with taps, but it is desirable in
both cases, to remove the rough surface the work acquires in the
foundry or forge, in order to economize the tools ; and the best
works are either bored or turned cylindrically to the true diame-
ters corresponding with the screwing tools.
The bolt to be screwed is mostly fixed in the tail vice vertically,
but sometimes horizontally, the dies are made to apply fairly, and
a little oil is applied prior to starting. As a more expeditious
method suitable to small screws, the work is caused to revolve in
the lathe, whilst the diestock is held in the hand ; and larger
screws are sometimes marked or lined out whilst fixed in the vice,
the principal part of the material is then removed with a chasing
tool or hand-screw tool, and the screw is concluded in the die-
stocks. In cutting up large screw bolts, two individuals are re-
quired to work the screw stocks, and they walk round the standing
vice or screwing clamp, which is fixed to a pedestal in the middle
of the workshop.
For screwing large numbers of bolts, the engineer employs the
"bolt-screwing machine, which is a combination of the ordinary taps
and dies, with a mandrel, driven by steam-power. In the machine
the mandrel revolves, traverses, and carries the bolt, whilst the
dies are fixed opposite to the mandrel ; or else the mandrel carries
the tap, and the nut to be screwed is grasped opposite to it. In
another machine, the mandrel does not traverse, it carries the bolt,
and the dies are mounted on a slide ; or else the mandrel carries
the nut, and the tap is fixed on the slide. The tap or die gives the
traverse in every case, and the engine and strap supply the muscle ;
of course the means for changing the direction of motion and
closing the dies, as in the hand process, are also essential.
The screwing table is a useful modification of the bolt machine,
intended to be used for small bolts, and to be worked by hand.
The mandrel is replaced by a long spindle running loosely in two
Figs. 483
484.
438
THE PRACTICAL METAL-WORKER S ASSISTANT.
bearings ; the one end of the spindle terminates in a small wheel
with a winch-handle, the other in a pair of jars closed by a screw.
The jaws embrace the head of the bolt, which is presented opposite
to dies tnat are fixed in a vertical frame or stock, and closed by a
loaded lever to one fixed distance. In tapping the nut, it is fixed
in the place before occupied by the dies, and the spindle then used
is bored up to receive the shank of the tap, which is fixed by a
side screw. This machine insures the rectangular position of the
several parts, and the power is applied by the direct rotation of a
hand wheels.
It will be gathered from the foregoing remarks, that the die-
SCREW-CUTTING TOOLS. 439
stock is an instrument of most extensive use, and it would indeed
almost appear as if every available construction had been tried,
with a general tendency to foster the cutter, and to expunge the
surface friction or rubbing action; by the excess of which latter
the labor of work is greatly increased, and risk is incurred of
stretching the thread.
Figures 483 and 484 show a shaping machine, built at the
Lowell Machine Shop, Lowell, Mass. Many of the machines built
at the Lowell Machine Shop, were much improved by W. B.
Bennet. This shaping and planing instrument will plane either
flat or curved surfaces.
The tool bar is moved by a variable crank adjustable to any
length of motion not exceeding eight inches. It has a self-acting
horizontal and circular feed motion, with a hand-feed motion for
internal curves.
Figs. 485, 486 show a gear-cutting machine manufactured at the
Lowell Machine Shop, Lowell, Massachusetts. The dividing plate
is forty-eight inches in diameter. This machine will cut every
number of teeth up to 133, and every even number to 268, also 272,
276, and 360 teeth.
The cutter stock is so arranged as to move either horizontally
or vertically, or at any angle, so as to cut bevel, spur, and spiral
wheels and gearing.
SCREWS CUT BY HAND IN THE COMMON LATHE. — Great num-
bers of screws are required in works of wood, ivory and metal,
that cannot be cut with the taps and dies, or the other apparatus
hitherto considered. This arises from the nature of the materials,
the weakness of the forms of the objects, and the accidental pro-
portions of the screws, many of which are comparatively of very
large diameter and inconsiderable length. These, and other cir-
cumstances, conspire to prevent the use of the diestocks for objects
such as the screws of telescopes and other slender tubes, those on
the edges of disks, rings, boxes, and very many similar works.
Screws of this latter class are frequently cut in the lathe with
the ordinary screw tool, and by dexterity of hand alone; there is
little to be said in explanation of the apparatus and tools, which
then consist solely of the lathe with an ordinary mandrel incapable
of traversing endways, and the screw tools or the chasing tools,
with the addition of the arm rest.
The screw tool held at rest would make a series of rings, because
at the end of the first revolution of the object, the points ABC
of the tool would fall exactly into the scratches ABC commenced
respectively by them. But if, in its first revolution, the tool is
shifted exactly the space between two of its teeth, at the end of the
revolution, the point B of the tool drops into the groove made by
the point A, and so with all the others, and a true screw is formed,
or a continuous helical line, which appears in steady lateral motion
during the revolution of the screw in the lathe.
It is likely the tool will fail exactly to drop into the groove, but
440
THE PRACTICAL METAL-WORKER'S ASSISTANT.
if the difference be inconsiderable, a tolerably good screw is never-
theless formed; as the tool being moved forward as equally as the
hand will allow, corrects most of the error. But if the difference
be great, the tool finds its way into the groove with an abrupt
break in the curve ; and during the revolution of the screw, as it
progresses it also appears to roll about sideways, instead of being
quiescent, and is said by workmen to be " drunk :" this error is
frequently beyond correction.
It sometimes happens that the tool is moved too rapidly, and
that the point C drops into the groove commenced by A ; in this
case the coarseness of the groove is the same as that of the tool,
but the inclination is double that intended, and the screw has a
double thread, or two distinct helices instead of one; the tool may
pass over three or four intervals and make a treble or quadruple
thread, but these are the results of design and skill, rather than of
accident.
On the other hand, from being moved too slowly, the point B
of the tool may fail to proceed so far as the groove made by A,
but fall midway between A and B ; in this case the screw has half
the rise or inclination intended, and the grooves are as fine again
as the tool; other accidental results may also occur which it is
unnecessary to notice.
ON CUTTING SCREWS IN LATHES WITH TRAVERSING MANDRELS.
— One of the oldest, most simple, and general apparatus for cutting
short screws in the lathe, by means of a mechanical guidance, is
the screw- mandrel or traversing-msmdrQl, which appears to have been
known almost as soon as the iron mandrel itself was introduced.
Fig. 487.
Figure 487 is copied from an old French mandrel mounted in
a wooden frame, and with tin collars cast in two parts ; the upper
halves of the collars are removed to show the cylindrical necks of
the mandrel, upon the shaft of which are cut several short screws.
In ordinary turning, the retaining koy k, which is shown detached
in the view k't prevents the mandrel from traversing, as its angular
SCREW-CUTTING TOOLS. 441
and circular ridge enters the groove in the mandrel ; but although
not represented, each thread on the mandrel is provided with a
similar key, except that their circular arcs are screw-form instead of
angular. In screw cutting, k is depressed to leave the mandrel at
liberty ; the mandrel is advanced slightly forward, and one of the
screw-keys is elevated by its wedge until it becomes engaged with
its corresponding guide-screw, and now as the mandrel revolves,
it also advances or retires in the exact path of the screw selected.
The modern screw-mandrel lathe has a cast-iron frame, and
hardened steel collars which are not divided ; the guide screws are
fitted as rings to the extreme end of the hardened steel mandrel,
and they work in a plate of brass, which has six scollops, or semi-
circular screws upon its edge. When this mandrel is used for
plain turning, its traverse is prevented by a cap which extends
over the portion of the mandrel protruding through the collars.
In cutting screws with either the old or modern screw-mandrel,
the work is chucked, and the tool is applied, exactly in the man-
ner of turning a plain object ; but the mandrel requires an alter-
nating motion backwards and forwards, somewhat short of the
length of the guide screw ; this is effected by giving a swinging
motion or partial revolution to the foot wheel. The tool should
retain its place with great steadiness, and it is therefore often fixed
in the sliding rest, by which also it is then advanced to the axis
of the work with the progress of the external screw ; or by which
it is also removed from the centre in cutting an internal screw.
To cut a screw exceeding the length of traverse of the mandrel,
the screw tool is first applied at the end of the work, and when as
much has been cut as the traverse will admit, the tool is shifted
the space of a few threads to the left, and a further portion is cut ;
and this change of the tool is repeated until the screw attains the
full length required. When the tool is applied by hand, it readily
assumes its true position in the threads ; when it is fixed in the
slide rest, its adjustment requires much care.
In screwing an object which is too long to be attached to the
mandrel by the chuck alone, its opposite extremity is sometimes
supported by the front centre or popit-head ; but the centre point
must then be pressed up by a spring, that it may yield to the
advance of the mandrel : this method will only serve for very
slight works, as the pressure of the screw-tool is apt to thrust the
work out of the centre. It is a much stronger and more usual plan,
to make the extremity or some more convenient part of the work
cylindrical, and to support that part within a stationary cylindrical
bearing, or collar plate, which retains the position of the work not-
withstanding its helical motion, and supplies the needful resistance
against the tool.
The amateur who experiences difficulty in cutting screws flying.
or with the common mandrel and hand-tool unassistedly, will find
the screw-mandrel an apparatus by far the most generally convenient
for those works, in wood, ivory, and rnetal turning, to which the
442
THE PRACTICAL METAL-WORKER'S ASSISTANT.
screw box and the taps and dies are inapplicable ; for the screw-
mandrel requires but a very small change of apparatus, and what-
ever may be the diameter of the work, it insures perfect copies of
the guide screws, the half dozen varieties of which will be found
to present abundant choice as to coarseness, in respect to the ordi-
nary purposes of turning.
ON CUTTING SCREWS IN LATHES WITH TRAVERSING TOOLS.- -A
great number of the engines for cutting screws, and also of the
other shaping and cutting engines now commonly used, are clearly
to be traced to a remote date, so far as their principles are con-
cerned.
For instance, the germs of many of these cutting machines, in
which the principles are well developed, will be found in the
primitive rose engine machinery with coarse wooden frames, and
arms, shaper plate, cords, pulleys, and weights, described in the
earliest works on the lathe, whilst many are as distinctly but more
carefully modeled in metal, in the tools used in clock and watch
making, many of which have also been published.
The principles of these machines being generally few and simple,
admit of but little change ; but the structures, which are most
, nay, almost endless, have followed the degrees of excel-
Fig. 488.
Jence of the constructive arts at the periods at which they have
been severally made, combined with the inventive talent of their
projectors.
In most of the screw-cutting machines a 'previously-formed
gcrew is employed to give the traverse ; such are copying machines,
and will form the subject of the present section ; and a few other
SCREW-CQTTIXG TOOLS.
443
engines serve to originate screws, by the direct employment of an
inclined plane, or the composition of 21 rectilinear and a circular
motion.
The earliest screw-lathe known to the author bears the date of
1569, and this curious machine, which is represented in Fig. 488,
is thus described by its inventor, Besson: "Esptice de Tour en nulle
part encore veue tt qui riest sans subtilite, pour engraver petit a petit la
Vis a Ventour de tout Figure ronde et solide, voire mesmes ovale"
The tool is traversed alongside the work by means of a guide-
screw, which is moved simultaneously with the work to be operated
upon, by an arrangement of pulleys and cords too obvious to require
explanation. It is however worthy of remark, that bad and im-
perfect as the constructive arrangement is, this early machine is
capable of cutting screws of any pitch, by the use of pulleys of
different diameters; and right and left-hand screws at pleasure, by
crossing or uncrossing the cord; and also that in this first machine
the inventor was aware that a screw-cutting-lathe might be used
upon elliptical, conical, and other solids.
The next illustration, Fig. 489, represents a machine described as
Fig. 489.
"A Lathe in which without the common art all sorts of screws and
other curved lines can be made ;" this was invented by M. Grand-
jean prior to 1729. The constructive details of this machine,
which are also sufficiently apparent, are in some respects superior
to those in Besson's ; but the two are alike open to the imperfec-
tion due to the transmissions of motion by cords; and Grandjean's
is additionally imperfect, as the scheme represented will fail to
produce an equable traverse of the mandrel compared with its
revolution, owing to the continual change in the angular relations
between the arms of the bent lever, and the mandrel and cord
respectively. Sometimes the spiral board or templet s, is attached
444 THE PRACTICAL METAL-WORKER^ ASSISTANT.
to the bent lever to act upon the end of the mandrel ; this also is
insufficient to produce a true screw in the manner proposed.
Several of the engines for cutting screws appear to be derived
from those used for cutting fusees, or the short screws of hyperbo-
lical section, upon which the chains of clocks and watches are
wound, in order to counteract the unequal strength of the different
coils of the spiral springs. The fusee engines, which are very
numerous, have in general a guide-screw from which the traverse of
the tool is derived, and the illustration, Fig. 490, selected from an
old work published in 1741, is not only one of the earliest, but
also of the most exact of this kind ; and it exhibits likewise the
primitive application of change wheels, for producing screws of
varied coarseness from one original.
This instrument is nearly thus described by Thiout: "A lathe
which carries at its extremity two toothed wheels ; the upper is
attached to the arbor, the clamp at the end of which holds the axis
of the fusee to be cut, the opposite extremity is retained by the
centre; the fusee and arbor constitute one piece, and are turned by
the winch handle. The lower wheel is put in movement by the
upper, and turns the screw which is fixed in its centre ; the nut
can traverse the entire length of the screw, and to the nut is
strongly hinged the lever that holds the graver or cutter, and
which is pressed up by the hand of the workman. Several pairs
of wheels are required, and the smaller the size of that upon the
mandrel the less is the interval between the threads of the fusee."
Fig. 490.
In the general construction of the fusee engine, the guide-screw
and the fusee are connected together on one axis, and are moved
by the same winch handle ; the degree of fineness of the thread on
the fusee is then determined by the intervention of a lever gener-
ally of the first order ; a great variety of constructions have been
made on this principle. Three are described in Thiout's Treatise :
namely, in plates 25, 26, and 27, the first by Eegnaud de Chaalon.
The mode of action will be moie clearly seen in the next figure,
SCREW-CUTTING TOOLS.
445
Fig. 491.
wherein precisely the same movements are applied to the lathe for
the purpose of cutting ordinary screws.
The apparatus now referred to is that invented by Mr. Healey
of Dublin, an amateur; it is universal, or capable within certain,
limits of cutting all kinds of screws, either right or left-handed,
and is represented in plan in Fig. 491, in which C is the chuck
which carries the work to be screwed, and t is the tool which lies
upon r r' the lathe-rest, that is placed at right angles to the bearer,
and is always free to move in its socket s, as on a centre, because
the binding screw is either loosened or removed.
On the outside of the chuck C is cut a coarse guide screw, which
we will suppose to be right-handed. The
nut n n, which fits the screw of the chuck,
is extended into a long arm, and the latter
communicates with the lathe-rest by the
connecting rod c c. As the lathe revolves
backwards and forwards the arm n (which
is retained horizontally by a guide pin g)
traverses to and fro as regards the chuck
and work, and causes the lathe-rest r r',
to oscillate in its socket s. The distance
s t being half s rr, a right-handed screw of
half the coarseness of the guide will be
cut ; or the tool being nearer to, and on | Q o y-f^ —
the other side of, the centre s, as in the _° ° fl ^
dotted position t', a finer and left-hand
screw will be cut.
The rod c c may be attached indiffer-
ently to any part of n n, but the smallest
change of the relation of s t to s r' would
mar the correspondence of screws cut at different periods, and there-
fore t and r should be united by a swivel-joint capable of being fixed
at any part of the lathe-rest rr' .
The apparatus represented in plan in Figs. 492 and 493, although
it does not present the universality of the last, is quite correct in
Figs. 492
493.
its action ; it is evidently a combination of the fixed mandrel, and
the old screw mandrel, Fig. 487. Four different threads are cut on
tl;e tube which surrounds the mandrel, and the connection between
446 THE PRACTICAL METAL-WORKERS ASSISTANT.
tlfe guide screw and the work is by the long bar b b, which carries
at the one end a piece g filed to correspond with the thread, and at
the other a socket in which is fixed a screw tool t, corresponding
with the guide at the time employed.
The lathe revolves with continuous motion ; and the long bar or
rod being held by the two hands in the position shown, the guide g
and the tool t are traversed simultaneously to the left by the screw
guide ; and when tj^e tool meets the shoulder of the work both
hands are suddenly withdrawn and the bar is shifted to the right
for a repetition of the cut, and so on until the completion of the
screw. The guide g is supported upon the horizontal plate p,
which is parallel with the mandrel, and the tool t lies upon the
lathe rest r.
Beneath the tool is a screw which rubs against the lathe rest r,
and serves as a stop ; this makes the screw cylindrical or conical,
according as the rest is placed parallel or oblique. For the inter-
nal screw the tool is placed parallel with the bar, as in Fig. 493 ;
and the check screw is applied on the side towards the centre
against a short bar parallel with the axis of the lathe.
None of the machines which have been hitherto described are
proper for cutting the accurate screws, of considerable length or
of great diameter, required in the ordinary works of the engineer ;
but these are admirably produced by the screw-cutting lathes, in
which the traverse of the tool is effected by a long guide-screw,
connected with the mandrel that carries the work by a system of
change wheels after the manner employed a century back, as in
Fig. 490. The accuracy of the result now depends almost entirely
upon the perfection of the guide-screw, and which we will suppose
to possess very exactly 2, 4, 5, 6, or some whole number of threads
in every inch, although we shall for the present pass by the methods
employed in producing the original guide-screw, which thus serves
for the reproduction of those made through its agency.
The smaller and most simple application of the system of change
wheels for producing screws is shown in Fig. 494. The work is
attached to the mandrel of the lathe by means of a chuck, to which'
is also affixed a toothed-wheel marked M, therefore the mandrel,
the wheel and the work partake of one motion in common. The
tool is carried by the slide-rest, the principal slide of which is
placed parallel with the axis of the lathe as in turning a cylinder,
and upon the end of the screw near the mandrel is attached a tooth
wheel S, which is made to engage in M, the wheel carried by the
mandrel.
As the wheels are supposed to contain the same number of
teeth, they will revolve in equal times, or make continually turn
for turn; and therefore in each revolution of the mandrel and
work, the tool will be shifted in a right line, a quantity equal to
one thread of the guide-screw, and so with every coil throughout
its extent of motion. Consequently the motion of the two axes
being always equal and continuous, the screw upon the work wiU
SOKEW-CUTTING TOOLS. 447
become an exact copy of the guide-screw contained in the slide-
rest, that is, as regards the interval between its several threads, its
total length, and its general perfection.
But the arrows in M and S denote that adjoining wheels always
travel in opposite directions; when, therefore, the mandrel and
slide-rest are connected by only one pair of wheels, as in Fig. 494,
the direction of the copy screw is the reverse of that of the guide.
The right-hand screw being far more generally required in me-
chanism, when the combination is limited to its most simple form,
of two wheels only, it is requisite to make the slide-rest screw left-
handed, in order that the one pair .of wheels may produce right-
hand threads.
But a right-hand slide-rest screw may be employed to produce
at pleasure both right and left-hand copies, by the introduction of
either one or two wheels, between the exterior wheels M and S,
Fig. 494. Thus, one intermediate axis, to be called I, would pro-
duce a right-hand thread ; two intermediate axes, I I, would pro-
duce a left-hand thread, and so on alternately ; and this mode, in
addition, allows the wheels M and S to be placed at any distance
asunder that circumstances may require.
In making double thread screws the one thread is first cut, the
wheels are then removed out of contact, and the mandrel is moved
exactly half a turn before their replacement, the second thread is
then made. In treble threads the mandrel is twice disengaged,
and moved one- third of a turn each time, and so on.
When the intermediate wheels are employed, it becomes neces-
sary to build up from the bearers some description of pedestal, or
from the lathe-head some kind of bracket, which may serve to
carry the axes or sockets upon which the intermediate wheels re-
volve. These parts have received a great variety of modifica-
tions, three of which are introduced in the diagrams Figs. 495 to
497 ; the wheels supposed to be upon the mandrel are situated on
the dotted line M M, and those upon the slide-rest on the line- 8 S.
448
THE PRACTICAL METAL-WORKER'S ASSISTANT.
The rectangular bracket in Fig. 495 has two straight mortises ;
by the one it is bolted to the bearers of the lathe, and by the other
it carries a pair of wheels, whose pivots are in a short piece, which
may be fixed at any height or angle in the mortise, so that one or
both wheels, I I, may be used according to circumstances. In Fig,
496, the intermediate wheel, or wheels, are carried by a radial
496
497.
arm, which circulates around the mandrel, and is fixed to the lathe
head by a bolt passed through the circular mortise. In Fig. 496,
a similar radial arm is adjustable around the axis of the slide-rest
screw, in the fixed bracket.
Sometimes the wheel supposed to be attached to the slide-rest,
is carried by the pedestal or arm, fixed to the bed or headstock of
the lathe ; in order that a shaft or spindle may proceed from the
wheel S, and be coupled to the end of the slide rest screw, by a
hollow square or other form of socket, so as to enable the rest to
be placed at any part of the length of the bearer, and permit a
screw to be cut upon the end of a long rod.
The shaft sometimes terminates at each end in universal joints,
in order to accommodate any trifling want of parallelism in the
parts ; if, however, the shaft be placed only a few degrees oblique,
the motion transmitted ceases to be uniform, or it is accelerated
and retarded in every revolution, which is fatal in screw cutting.
This change in the position of the slide-rest is also needful in
cutting a screw which exceeds the length the rest can traverse, as
such long screws may then be made at two or more distinct opera-
tions; before commencing the second trip the tool is adjusted to
drop very accurately into the termination of that portion of the
screw cut in the first trip, which requires very great care, in order
that no falsity of measurement may be discernible at the parts
where the separate courses of the tool have met. This method of
proceeding has, however, from necessity been followed in produc-
ing some of the earliest of the long regulating screws, which have
served for the production of others by a method much less liable
to accident, namely, when the cut is made uninterruptedly through-
out the extent of the work.
SCREW-CUTTIXG TOOLS. 449
In the larger application of the system of change-wheels, the
entire bed of the lathe is converted into a long slide-rest, the tool
carriage with its subsidiary slides for adjusting the position of the
tool, then traverses directly upon the bed ; this mode has given
rise to the name " traversing or slide-lathe," a machine which has
received, and continues to receive, a variety of forms in the hands
of different engineers. It would be tedious and unnecessary to.
attempt the notice of their different constructions, which neces-
sarily much resemble each other ; more especially as the principles
and motives, which induce the several constructions and practices,
rather than the precise details of apparatus, are here under con-
sideration.
The arrangement for the change- wheels of a screw-cutting lathe
given in Fig. 498, resembles the mode frequently adopted. The
guide-screw extends through the middle of the bed, and projects at
the end ; there is a clasp nut, so that when required, the slide-rest
may be detached from the screw and moved independently of the
same. The train of wheels is placed at the left extremity of the
lathe ; there is a radial arm which circulates
around the end of the main screw, the arm Fig. 498.
has one or two straight mortises, in which
are fixed the axes of the intermediate wheels,
and there are two circular mortises, by which M
the arm may be secured to the lathe bed, -in
any required position, by its two binding S
screws.
On comparing the relative facilities for cut-
ting screws, either with the slide-rest furnish-
ed with a train of wheels, or with the travers-
ing or screw-cutting lathe, the advantage will
be found greatly in favor of the latter ; for in-
stance : —
With the slide-rest arrangement, Fig. 494,
the work must be always fixed in a chuck to which the first ol
the change- wheels can be also attached; the wheels frequently
prevent the most favorable position of the slides from being
adopted ; and in cutting hollow screws the change-wheels entirely
prevent the tool carriage of the slide-rest from being placed oppo-
site to the centre, and therefore awkward tools, bent to the rectan-
gular form, must be then used. The slide-rest also requires fre-
quent attention to its parallelism with the axis of the lathe, or the
screws cut will be conical instead of cylindrical.
With the traversing lathe, from the wheels being at the back of
the mandrel, no interference can possibly arise from them, and
consequently the work may be chucked indiscriminately on any
of the chucks of the lathe ; every position may be given to the
slide carrying the tool, and therefore the most favorable, or that
nearest to the work, may be always selected, and the tools need
not be crooked. As the tool carriage traverses at once on the
29
450 THE PRACTICAL METAL-WORKER'S ASSISTANT.
bearers of the lathe, the adjustment for parallelism is always true,
and the length of traverse is greatly extended.
The system of screw-cutting just explained is very general and
practical : for instance, one long and perfect guide-screw (which
we will call the guide), containing 2, 4, 6, 8, 10, or any precise
number of threads per inch having been obtained, it becomes \vrv
easy to make from it subsequent screws, (or copies) which shall be
respectively coarser and finer in any determined degree. The
principle is, that whilst the copy makes one revolution, the guide
must make so much of one revolution, or so many, as shall traverse
the tool the space required between each thread of the copy ; and
this is accomplished by selecting change-wheels in the proportions
of these quantities of motion, or in other words, in the proportion
required to exist between the guide-screw and the copy.
In explanation, we will suppose the guide to have 6 threads per
inch, and that copies of 18, 14, 12 J, 8, 3, 2, 1, threads per inch arc
required ; the two wheels must be respectively in the proportions
of the fractions -fs, fi, T62 I, f, £, £, ?, the guide being constantly
the numerator. The numerator also represents the wheel on the
mandrel, and the denominator that on the guide-screw ; any multi-
ples of these fractions may be selected for the change- wheels to
be employed.
For example, any multiples of -j6g, as Jy, !f, f J, etc., will pro-
duce a screw of 18 threads per inch, the first and finest of the
group ; and any multiples of ?, as, Jj?, Vo0* etc., will produce a
screw of 1 thread per inch, which is the last and coarsest of those
given.
Screws 2, 4, or 6 times as fine will result from the interposing
a second pair of wheels, respectively multiples of J, j-7 J, and placed
upon one axis.
For instance, the pair of wheels 'I-*, used for producing a screw
of 18 threads per inch, would, by the combination A, produce a
copy three times as fine, or a screw of 54 threads per inch. Fig.
496 represents the wheels referred to in combination A, and Fig.
497 those in combination B.
Combination A. Combination B. Combination C.
M Interm. S M Interm. S M Interrn. S.
24 60 120 24 27 53
20 72 72 20 39 107
And the wheels *•££ used for the screw of one thread per inch,
would by the combination B, produce a copy three times as coarse,
or of three inches rise. Whatsoever the value of the intermediate
wheels, whether multiplies of f , f, f, etc., they produce screws re-
spectively of |, J, f, the pitches of those screws, which would be
otherwise obtained by the two exterior wheels alone ; and in this
manner a great variety of screws, extending over a wide range of
pitch, may be obtained from a limited number of wheels.
For instance, the apparatus HoltzapfFel and Co. have recently
SCREW- CUTTING TOOLS. 451
added to'tlte slide rest, after the manner of Figs. 494 and 496, has
a series of about fifteen wheels, of from 15 to 144 teeth, employed
with a screw of 10 threads per inch : several hundred varieties of
screws may be produced by this apparatus, the finest of which has
320 threads per inch, the coarsest measures 7 1 inches in each coil
or rise : and the screws may be made right or left-handed, double,
triple, quadruple, or of any number of threads. The finest com-
binations are only useful for self-acting turning ; those of medium
coarseness serve for all the ordinary purposes of screws ; whilst
the very coarse pitches are much employed in ornamental works,
and in cutting these coarse screws the motion is given to the slide-
rest screw, and by it communicated to the mandrel.
The value of any combination of wheels may be calculated as
vulgar fractions, by multiplying together all the driving wheels as
numerators, and all the driven wheels as denominators, adding also
the fractional value, or pitch, of the guide-screw ; thus in the first
example A : —
24 x 20 x 1 = 480 1
or reduced to its lowest terms — .
60 x 72 x 6 = 25920 54
The fraction denotes that ^th of an inch is the pitch of the screw,
or the interval from thread to thread ; also that it has 54 threads
in each inch, and which is called the rate of the screw.
And in C, the numbers in which example were selected at ran-
dom, the screw would be found to possess rather more than 35
threads per inch.
The fractions should be reduced to their lowest terms before cal-
culation, to avoid the necessity for multiplying such high numbers.
Thus the first example would become reduced to J x J x \ = s\,
and would be multiplied by inspection alone, as the numerators
and denominators may be taken crossways if more convenient; thus
f I is equal to J, and §g is also equal to £, fractions which are
smaller than ? and T65, the lowest terms respectively of §£ and f§;
the second case could not be thus treated, and the whole numbers
must there be multiplied, as they will not admit of reduction.
Other details will be advanced, and tables of the combinations of
the change- wheels will be also given, in treating of the practice of
cutting screws.
27 x 39 x 1 1114 1
- or reduced to its lowest terms .
53 x 107 x 6 39026 35T}h
In imitation of the method of change- wheels, the slide-rest screw
is sometimes moved by an arrangement of catgut bands, resem-
bling that represented in Besson's screw-lathe, page 442.
One band proceeds from the pulley on the mandrel to a spindle
overhead having two pulleys, and a second cord descends from
this spindle to a pulley on the slide-rest. This apparatus has been
452 THE PRACTICAL METAL-WORKER'S ASSISTANT.
applied to cutting the expanding horn snakes. See Manuel de Tour-
neur, first edit., 1796, vol. ii., plate 21 ; and second edit., 1816, vol.
ii., plate 16.
The method offers facility in cutting screws of various pitches,
by changing the pulleys, and also either right or left-hand screws,
by crossing or uncrossing one of the bands.
The plan is unexceptionable, when applied for traversing the
tool slowly for the purpose of turning smooth cylinders, or sur-
faces (which is virtually cutting a screw or spiral of about 100
coils in the inch); and in the absence of better means, pulleys and
bands are sometimes used in matching screws of unknown or irreg-
ular pitches, by the tedious method of repeated trials; as on
slightly reducing, with the turning tool, the diameter of either of
the driving pulleys, the screw or the work becomes gradually
finer; and reducing either of the driven pulleys makes it coarser ;
but the mode is scarcely trustworthy, and is decidedly far inferior
to its descendant, or the method of change-wheels.
The screw tools, or chasing tools, employed in the traversing
lathes for cutting external and internal screws, resemble the fixed
tools generally, except as regards their cutting edges; the follow-
ing figures, 499 to 501, refer to angular threads, and 502 and 503
to square threads.
Angular screws are sometimes cut with the single point, Fig.
499, a form which is easily and correctly made ; the general angle
of the point is about 55° to 60°, and when it is only allowed to
cut on one of its sides or bevels, it may be used fearlessly, as the
shavings easily curl out of the way and escape. But when both
sides of the single point tool are allowed to cut, it requires very much
more cautious management; as in the latter case, the duplex shav-
ings being disposed to curl over opposite ways, they pucker up as
an angular film, and in fine threads they are liable to break the
point of the tool, or to cause it to dig into, and tear the work.
Sometimes, also, a fragment of the shaving is wedged so forcibly
into the screw by the end of the tool, that it can only be extricated
by a sharp chisel and hammer.
In cutting angular screws, it is very much more usual and ex-
peditious to employ screw tools with many points, which are made
in the lathe by means of a revolving cutter or hob, Figs. 447 and
448, page 427. Screw tools with many points, are always required
for those angular threads which are rounded, at the top and bottom,
and which are thence called rounded or round threads.
To the screw tool for rounded threads is given the profile of
Fig. 500, which construction allows the tool to be inverted, so that
the edges may be alternately used for the purpose of equalizing
the section of the thread. In making the tool 500, the hob (which
is dotted) is put between centres in the traversing lathe, and those
wheels are applied which would serve to cut a screw of the same
pitch as the hob ; the bar of steel is then fixed in the slide-rest, so
that the dotted line or the axis of the tool intersects the centre of
SCREW-CUTTING TOOLS.
453
the hob, The tool is afterwards hollowed on both sides with the
file, to facilitate the sharpening, and it is then hardened. In using
the tool, it is depressed until either edge comes down to the radius,
proceeding from the (black) circle, which is supposed to represent
the screw to be cut; the depression gives the required penetration
to the upper angle, and removes the lower out of contact.
In the chasing tool represented in Fig. 501, the cutter, c, is made
as a ring of steel which is screwed internally to the diameter of
the bolt, and turned externally with an undercut groove, for the
small screw and nut by which it is held in an iron stock, s, formed
of a corresponding sweep; for distinctness the cutter and screw
are also shown detached. The centre of the curvature of the tool
is placed a little below the centre of the lathe, to give the angle of
Screiv Tools for Angular Threads.
Figs. 499
Screw Tools for Square Threads.
502
t-
f
501
separation or penetration; and after the tool has been ground away
in the act of being sharpened, it is raised up, until its points touch
a straight-edge applied on the line a a of the stock ; this denotes
the proper height of centre, and also the angle to which the tool is
intended to be hooked, namely, 10 degrees : each ring makes four
or five cutters, and one stock may be used for several diameters
of thread.
Angular thread screws are fitted to their corresponding nuts
simply by reduction in diameter ; but square thread screws require
attention both as to diameter and width of groove, and are conse-
quently more troublesome. Square thread screws are in general
of twice the pitch, or double the obliquity, of angular screws of
454 THE PRACTICAL METAL- WORKER'S ASSISTANT.
the same diameters ; and, consequently, the interference of angle
before explained as concerning the die-stocks, refers with a two-
fold effect to square threads, which are in all respects much better
produced in the screw-cutting lathe.
The ordinary tool for square thread-screws is represented in
two views in Fig. 502 ; the 'shaft is shouldered down so as to ter-
minate in a rectangular part which is exactly equal to the width
of the groove. In general the end alone of the tool is required
to cut, and the sides are beveled according to the angle of the
screw, to avoid rubbing against the sides of the thread. Tools
which cut upon the side alone are also occasionally used for ad
justing the width of the groove. In either case it requires con-
siderable care to maintain the exact width and height of the tool — •
the inclination of which should also differ for every change of
diameter.
To obviate these several inconveniences, the author several years
back contrived a tool-holder, Fig. 503, for carrying small blades
made exactly rectangular. In height, as at h, the blades are alike,
in width, w, they are exactly half the pitch of the threads, and
they are ground upon the ends alone. The parallel blades are
clamped in the rectangular aperture of the tool socket by the four
screws c c ; and when the screws s s, which pass through the cir-
cular mortises in the sockets, are loosened, the swivel-joint and
graduations allow the blades to be placed at the particular angle
of the thread, which is readily obtained by calculation, and is
estimated for the medium depth of the thread, or midway between
the extreme angles at the top and bottom.
One blade, therefore, serves perfectly for all screws of the same
pitch, both right and left-handed, and of all diameters. As the
tool exactly fills the groove, it works steadily, and the width of the
groove and the height of the centre of the tool are also strictly
maintained with the least possible trouble. The depth of the
groove, which is generally one-sixth more than its width, is read
off with great facility by means of the adjusting- screw of the slide-
rest ; especially if, as usual, the screw and its micrometer agree
with the decimal division of the inch.
The holder, Fig. 503, has been much and satisfactorily used for
screws from about 20 to 2 threads per inch ; but when the screw
is coarse and oblique, compared with its diameter, the blade is
ground away to the dotted line in h, and is sometimes beveled on
the sides almost to the upper edge, to suit the obliquity of the
thread, but without altering the extreme width of the tool.
The tools for external screws of very coarse pitch, are necessa-
rily formed in the lathe by aid of the corresponding wheels and a
revolving cutter bar resembling Fig. 415, p. 410. The soft tool is
fixed in the slide-rest, and is thereby carried against the revolving
cutter bar, 415, which has a straight tool, either' pointed or square
as the case may be. The end of the screw tool is thus shaped as
part of an external screw, the counterpart of that to be cut. The
SCREW-CUTTING TOOLS. 455
face of the screw tool is filed at right angles to the obliquity of the
thread, and the end and sides are slightly beveled for penetration
previously to its being hardened.
Internal square threads of small size are usually cut with taps
which resemble Fig. 445, p. 424, except in the form of the teeth.
When internal square threads are cut in the lathe, the tool assumes
the ordinary form of a straight bar of steel with a rectangular
point standing off at right angles, in most respects like the com-
mon pointed tool for inside work.
For very deep holes, and for threads of very considerable ob-
liquity, cutter bars, such as Fig. 415, p. 410, are used. The work
and the temporary bearings of the bar are all immovably fixed for
the time, and the bar advances through the bearings in virtue of
its screw-thread ; or otherwise a plain bar, having a cutter only,
and not being screwed, may be mounted between centres in the
screw lathe, and the work, fixed to the slide-rest, may traverse
parallel with the bar by aid of the change-wheels. The cutter bar
in some cases requires a ring to fill out the space between itself
and the hole, to prevent vibration ; and it is necessary to increase
the radial distance of the cutter between each trip, by a set screw,
or by slight blows of a hammer.
Very oblique inside cutters are turned to their respective forms
with a fixed tool, in a manner the converse of that explained
above; and some peculiarities of management are required in
using them, in order to obtain the under-cut form of the internal
thread.
In cutting screws in the turning lathe, the tool only cuts as it
traverses in the one direction; therefore whilst the cutter is
moved backwards, or in the reverse direction, for the succeeding
cut, it must be withdrawn from the work. Sometimes the tool is
traversed backwards by reversing the motion of the lathe ; and in
lathes driven by power, the back motion is frequently more rapid
than the cutting motion, to expedite the process ; at other times
the lathe is brought to rest, the nut is opened as a hinge, so as to
become disengaged from the screw, and the slide-rest is traversed
backwards by hand, or by a pinion movement, and the nut is again
closed on the screw, prior to the succeeding cut. This mode an-
swers perfectly for screws of the same thread as the guide, and for
those of 2, 4, 6, 8 times as coarse or as fine; but for those of 2J,
4J, or any fractional times the value of the guide screw, the clasp
nut cannot in general be employed advantageously.
The progressive advance of the tool between each cut, is com-
monly regulated by a circle of divisions or a micrometer on the
slide rest screw, which should always correspond with the decimal
division of the inch. The substance of the shaving may be pretty
considerable after the first entry is made, but it should dwindle
away to a very small quantity, towards the conclusion of the
screw. To avoid the necessity for taxing the memory with the
graduation at which the tool stood when it was withdrawn for the
456 THE PRACTICAL METAL-WORKER'S ASSISTANT.
back stroke, the author has been in the habit of employing a
micrometer exactly like that on the screw, which is set to the same
graduation, and serves as a remembrancer ; another method is to
employ an arm or stop, which fits on the axis of the screw or
handle with stiff friction, but nevertheless allows the tool to be
shifted the two or three divisions required for each cut.
In the screw lathe used by Mr. Roberts, the nut of the slide-
screw instead of being a fixture, is made with two tails as a fork,
which embraces an eccentric spindle ; by the half rotation of which
spindle, the nut together with the adjusting screw, the slide, and
the tool, are shifted, as one mass, a fixed distance to and from the
centre, between each cut ; so as first to withdraw and then to replace
the tool. Whilst the tool is running back, the screw is moved by
its adjusting screw and divisions, the minute quantity to set in the
tool for the succeeding cut, and the continual wear upon the adjust-
ing screw, as well as the uncertainty of its being correctly moved
to and fro by \he individual, are each avoided.
Sometimes, with the view of saving the time lost in running
back, two tools are used, so that the one may cut as the tool slide
traverses towards the mandrel, the other in the contrary direction.
An arrangement for this purpose, as applied to the screwing of
bolts in the lathe, is shown in Fig. 50-i ; / represents the front, and
b the back tool, which are mounted on the one slide s s, and all
three are moved as one piece by the handle h, which does not
require any micrometer.
504.
In the first adjustment, the wedge w, is thrust to the bottom of
the corresponding angular notch in the slide s, and the two tools
are placed in contact with the cylinder to be screwed. For the
first cut, the wedge is slightly withdrawn to allow the tool / to be
advanced towards the work ; and for the return stroke, the wedge
SCREY;- CUTTING TOOLS. 457
is again shifted under the observation of its divisions, and the slide
s s, is brought forwards, towards the workman, up to the wedgo ;
this relieves the tool / and projects b, which is then in adjustment
for the second cut ; and so on alternately. The command of the
two tools is accurately given by the wedge, which is moved a
small quantity by its screw and micrometer, between every alter-
nation of the pair of tools, by the screw h.
In cutting very long screws, the same as in turning long cylin-
drical shafts, the object becomes so slender, that the contrivance
called a backstay is always required for supporting the work in
the immediate neighborhood of the tool. The backstay is fixed
to the slide plate, or the saddle of the lathe which carries the tool,
and is- brought as near to the tool as possible; sometimes the dies
or bearings are circular, and fit around the screw ; at other times
they touch the same at two, three or four parts of the circle only.
Some of the numerous forms of this indispensable guide or back-
stay will hereafter be shown.
In using the screw-lathe with a backstay for long screws, it is a
valuable and important method, just at the conclusion, to employ a
pair of dies in tiie place usually occupied by the tool ; as they are
a satisfactory test for exact diameter, and they remove trifling-
errors attributable to veins and irregularities of the material,
which the fixed tool sometimes fails entirely to reduce to the gen-
eral surface. The tool and backstay may be each considered to be
built on the tops of pedestals more or less lofty, and therefore,
more susceptible of separation by elasticity, than the pair of dies
fixed in a small square frame. It has been judiciously proposed,
in effect, to link the backstay and turning tool together, by the
employment of a small frame carrying a semicircular die of lignum -
vitse, and a fixed turning tool, adjusted by a pressure screw; the
frame to be applied either in the hand alone or in the slide rest,
and to be inverted so that the shavings may fall away without,
clogging the cutter.
VARIOUS MODES OF ORIGINATING AND IMPROVING SCREWS. —
The improvement of the screw has given rise to many valuable
schemes and modes of practice, which have not been noticed in
the foregoing sections, notwithstanding their collective length.
These practices indeed could not consistently have been placed in
the former pages of this subject because some of them must be
viewed as refinements upon the general methods, the earlier notice
of which would have been premature ; and others exhibit various
combinations of methods pursued by different eminent individuals
with one common object, and are therefore too important to be
passed in silence, notwithstanding their miscellaneous nature.
To render this section sufficiently complete, it appears needful to
take a slight retrospective glance of the early and the modern modes
of originating screws and screw apparatus ; some account of the
former may be found in the writings of Pappus, who lived in the
fourth century.
453 . THE PRACTICAL METAL-WORKER'S ASSISTANT.
Iii the works of Pappus Alexandrinus, a Greek mathematician
of the fourth century, are to be found practical directions for making
screws.
The process is simply to make a templet of thin brass of the form
of a right-angled triangle, the angles of which are made in accord-
ance with the inclination of the proposed screw. This triangle is
then to be wrapped round the cylinder which is to be the desired
screw, and a spiral line traced along its edge. The screw is sub-
sequently to be excavated along this line. Minute practical direc-
tions are given not only for every step of this process, but also for
the division, setting out, and shaping the teeth of a worm-wheel of
any required number of teeth to suit the screw. (Vide Pappi
Math. Col., lib. viii. prob. xviii.)
The progressive stages which may be supposed to have been
formerly in pretty general use for originating screws, may be thus
enumerated :
1. The first screw-tap may be supposed to have been made by
the inclined templet, the file, and screw tool. It was imperfect in
all respects, and not truly helical, but full of small irregularities.
2. The dies formed by the above were considerably nearer to
perfection, as the multitude of pointed edges of 1 being passed
through every groove of the die, the threads of the latter became
more nearly equal in their rake or angle, and also in their distances
and form.
3. The screw cut with such dies would much more resemble a
true helix than 1 ; but from the irregularities in the first tap, the
grooves in the die 2 would necessarily be wide, and their sides,
instead of meeting as a simple angle, would be more or less filled
with ridges, and 3 would become the exact counterpart of 2.
4. A pointed tool applied in the lathe would correct the form of
the thread or groove in 3 without detracting from its improved
cylindrical and helical character, especially if the turning tool were
gradually altered from the slightly rounded to the acute form in
accordance with the progressive change of the screw. The latter
is occasionally changed end for end, either in the die-stocks or in
the lathe, to reverse the direction in which the tools meet the work,
and which reversal tends to equalize the general form of the thread.
5. The corrected screw 4, when converted into a master-tap,
would make dies greatly superior to 2 ; it would also serve for
cutting up screw tools ; and lastly,
6. The dies 5 would be employed for making the ordinary screws
and working taps ; and this completes the one series of screwing
apparatus..
One original tap having been obtained, it is often made sub-
servient to the production of others ; for example, a screw tool with
several points cut over the corrected original 4 would serve for
striking in the lathe other master-taps of the same thread but
different diameters. The process is so much facilitated by the per-
fection of the screw tool that a clever workman would thus, with-
SCREW-CUTTING TOOLS. 459
out additional correction, strike master-taps sufficiently accurate for
cutting up other dies larger or smaller than 4. Sometimes also the
dies 5 are used for marking out original taps a little larger or
smaller than 4.
As a temporary expedient the screw tool may be somewhat spread
at the forge fire to make a tool a little coarser, or it may be upset
for one a little finer, and afterwards corrected with a file ; or screw
tools may be made entirely with the file, and then employed for
producing, in the lathe, master-taps of corresponding degrees of
coarseness and of all diameters.
These are in truth some of the progressive modes by which, under
very careful management, great numbers of good useful screwing
apparatus have been produced, and which answer perfectly well for
all the ordinary requirements of " binding" or " attachment" screws ;
or as the cement by which the parts of mechanism and structures
generally are firmly united together, but with the power of separa-
tion and reunion at pleasure.
In this comparatively inferior class of screws considerable latitude
of proportion may be allowed, and whether or not their pitches or
rates have any exact relationship to the inch, is a matter of indiffer-
ence as regards their individual usefulness ; but in superior screws,
or those which may be denominated " regulating" and " micrometri-
cal" screws, it does not alone suffice that the screw shall be good in
general character, and as nearly as possible a true helix ; but it
must also bear some defined proportion to the standard foot or
inch, or other measure. The attainment of this condition has
been attempted in various ways, to some of which a brief allu-
sion was made, and a few descriptive particulars will now be
offered.
The apparatus for cutting original screws by means of a wedge
or inclined plane, appears to be derived from the old fusee engine,
a drawing of which is given in Fig. 505. In principle it is per-
fect, and it is also universal within the narrow limitation of its
structure.
The drawing is the half size of Fig. 1, Plate xvii., of Ferdinand
Berthoud's Essai sur L'fforlogerie, Paris, 1763. M. Berthoud says,
" The instrument is the most perfect with which I am acquainted ;
it is the invention of M. Le Lievre, and it has been reconstructed
and improved by M. Gideon Duval." The templet or shaper plate
determines the hyperbolical section of the fusee. The modifica-
tion, with an inclined plane, is due to Hindley, of York.
The handle h gives rotation to the work ; and at the same time,
by means of the rack r r, and the pinion fixed on its axis, the
handle traverses a slide which carries on its upper surface a bar i ;
the latter moves on a centre, and may be set at any inclination
by the adjusting screw and divisions ; it is then fixed by its clarnp
ing screws. The slide s carries the tool, and the end of this slide
rests against the inclined plane i through the intervention of a
saddle or swing piece. The slide atfd tool are drawn to the left
460
THE PRACTICAL METAL-WORKEIt'S ASSISTANT.
hand by the chain which is coiled round the barrel I, by means of
a spiral spring contained within it.
Fig.
Supposing the bar { % to stand square or at zero, no motion
would be impressed on the tool during its traverse, which we will
suppose to require 10 revolutions of the pinion. But if the bar
were inclined to its utmost extent, so that we may suppose the one
end to project exactly one inch beyond the other, in reference to
the zero line or the path of the slide, then during the 10 revolu-
tions of the screw the tool would traverse one inch, or the differ-
ence between the ends of the inclined bar i ; and it would thereby
cut a screw of the length of one inch, or the total inclination of the
bar, and containing ten coils or threads.
But the inclination of the bar is arbitrary, and may be any
quantity less than one inch, and may lean either to the right or
left ; consequently the instrument may be employed in cutting all
right or left-hand screws, not exceeding 10 turns in length, nor measur-
ing in their total extent above one inch, or the maximum inclination
of the bar.
The principle of this machine may be considered faultless ; but
in action it will depend upon several niceties of construction, par-
ticularly the straightness of the slide and inclined bar, the equality
of the rack and pinion, and the exact contact between the tool slide
and the inclined plane. These difficulties augment very rapidly
with the increase of dimensions ; and probably the machine made
by Mr. Adam Reid exclusively for cutting screws, is as large as
SCKEW-CUTTING TOOLS. 461
can be safely adopted. The inclined plane is 44 inches long, but
the work cannot exceed 1 ^ths inch diameter, 2 J inches long, or
ten threads in total length. The application of the inclined plane
to cutting screws is therefore too contracted for the ordinary wants
of the engineer, which are now admirably supplied by the screw-
cutting lathes with guide screws and change wheels.
The accuracy of screws has always been closely associated with
the successful" performance of engines for graduating circles and
right lines, and the next examples will be extracted from the pub-
lished accounts of the dividing engines made by Mr. Eamsden.
This eminent individual received a reward from the Board of
Longitude, upon the condition that he would furnish for the benefit
of the public a full account of the methods of constructing and
using his dividing machines, and which duly appeared in the
following tracts : " Description of an Engine for Dividing Mathe-
matical Instruments, by Kamsden, 4to., 1777." Also, " Descrip-
tion of an Engine for Dividing Straight Lines, by Eamsden, 4to.,
1779, from which the following particulars are extracted :
The circular dividing engine consisted of a large wheel moved
by a tangent screw ; the wheel was 45 inches diameter, and had
2160 teeth, so that six turns of the tangent screw moved the circle
one degree ; the screw had a micrometer, and also a ratchet-wheel
of 60 teeth — therefore one tooth equalled one-tenth of a minute
of a degree. The screw could be moved a quantity equal to one
single tooth, or several turns and parts, by means of a cord and
treadle, so that the circular works attached to the dividing wheel
could be readily graduated into the required numbers by setting
the tangent screw to move the appropriate quantities. The divid-
ing knife or diamond point always moved on one fixed radial line
by means of a swing-frame.
"In ratching or cutting the wheel," says Mr. Ramsden, "the
circle was divided with the greatest exactness I was capable of,
first into 5 parts, and each of these into 3 ; these parts were then
bisected 4 times; this divided the wheel into 240 divisions, each
intended to contain 9 teeth. The ratching was commenced at each
of the 240 divisions by setting the screw each time to zero by its
micrometer, and the cutter frame to one of the great divisions by
the index ; the cutter was then pressed into the wheel by a screw,
and the cutting process was interrupted at the ninth revolution of
the screw. It was resumed at the next 240th division (or nine
degrees off), as at first, and so on.
This process was repeated three times round the circle, after
which the ratching was continued uninterruptedly around the wheel
about 300 times ; this completed the teeth with satisfactory accu-
racy. The tangent screw was subsequently made, as explained in
the text.
The first application of the tangent screw and ratchet to the pur-
poses of graduation, appears to have been in the machine for ciu-
ting clock and watch wheels, by Pierre Fardoil; see plate 23 01
462 THE PRACTICAL METAL-WORKEIi's ASSISTANT.
Thiout's Traiti (T fforkgcrie, etc. Paris, 1741. At page 55 is
given a table of ratchets and settings for wheels with from 102 to
800 teeth.
In Mr.Ramsden's description of his dividing engines for circles, he
says: "Having measured the circumference of the dividing wheel, I
found it would require a screw about one thread in a hundred coarser
than the guide-screw." He goes on to explain that the guide-screw
moved a tool fixed in a slide carefully fitted on a triangular bar, an
arrangement equivalent to a slide-rest and fixed tool: the screw to be
cut was placed parallel with the slide, and the guide-screw and copy
were connected by two change wheels of 198 and 200 teeth (numbers
in the proportion required between the guide and copy), with an in-
termediate wheel to make the threads on the two screws in the same
direction. As no account is given of the mode in which the guide-
screw was itself formed, it is to be presumed it was the most correct
screw that could be obtained, and was produced by some of the means
described in the beginning of the present sections.
Mr. Ramsden employed a more complex apparatus in originat-
ing the screw of his dividing engine for straight lines, which it
was essential should contain exactly 20 threads in the inch ; a con-
dition uncalled for in the circular engine, in which the equality of
the teeth of the wheel required the principal degree of attention.
This second screw-cutting apparatus, which may be viewed as an
offspring of the circular dividing engine, is represented in plan, in
Fig. 509, and may be thus briefly explained.
Fig. 509.
The guide-screw G is turned round by the winch, and in each
revolution moves the larger tangent wheel one tooth : the tangent
wheel has a small central box or pulley p, to which is attached
the one end of an elastic slip of steel, like a watch-spring; the
other end of the slip is connected with the slide'*, that carries the
tool t, in a right line besides the screw C, which latter is the piece
to be cut ; and C is connected with the guide-screw G, by a bevel
pinion and wheel g, and c, as 1 to 6.
SCREW-CUTTING TOOLS. 463
To proportion the traverse of the tool to the interval or pitch of
the screw, two dots were made on the slide 5, exactly five inches
asunder ; and in that space the screw should contain 100 coils, to
be brought about by 600 turns of the handle. The guide-screw
was moved that number of revolutions, and the diameter of p was
reduced by trial, until the 600 turns traversed the slide exactly
from dot to dot ; these points were observed at the time through a
lens placed in a fixed tube, and having a fine silver wire stretched
diametrically across the same as an index.
See " Description of an Engine for Dividing Straight Lines."
In the construction of his dividing, engine for straight lines,
Ramsden very closely followed his prior machine for circular
lines, if we conceive the wheel spread out as a rectangular slide.
On the one edge of the main slide which carried the work, was cut
a screw-form rack, with twenty teeth per inch, which was moved
by a short fixed screw of the same pitch, by means of ratchets of
50, 48, or 32 teeth respectively; the screw could be moved a
quantity equal to one single tooth, or to several turns and parts,
by means of a treadle. To obtain divisions which were incompa-
tible with the sub-division of the inch into 1000, 960 or 640 parts,
the respective values of one tooth, the scale was laid on the slide
at an angle to the direction of motion ; when the swing frame was
placed to traverse the knife at right angles to the path of the slide,
the graduations were lengthened ; when the knife was traversed at
right angles to the oblique position of the scale being divided, they
were shortened. This was to a small degree equivalent to having
a screw of variable length. In cutting the screw-form teeth of the
rectilinear dividing engine, the entire length, namely, 25.6 inches,
was first divided very carefully by continual bisection into spaces
of eight-tenths of an inch, by hand as usual, and the screw-cutter
was placed at zero at each of these divisions, pressed into the edge
of the slide, and revolved sixteen times; after .three repetitions at
each of the principal spaces, the entire length was ratched continu-
ously until the teeth were completed.
With the view of producing screws of exact values, engineers
have employed numerous modifications of the chain or band of
steel, the inclined knife, the inclined plane, and indeed each of the
known methods, which, however, were remodelled as additions to
the ordinary turning- lathe with a triangular bar.
Some give a preference to the inclined knife, applied against a
cylinder revolving in the lathe, by means of a slide running upor.
the bar of the lathe ; which, besides being very rapid, reduced the
mechanism to its utmost simplicity. This made the process to de-
pend almost alone on the homogeneity of the materials, and on the
relation between the diameter of the cylinder and the inclination
of the knife ; whereas in a complex machine, every part concerned
in the transmission of motion, such as each axis, wheel and slide7
entails its risk of individual error, and may depreciate the accuracy
of the result ; and to these sources of disturbance, must be added
464: THE PRACTICAL METAL-WORKER'S ASSISTANT.
those due to change of temperature, whether arising from the at-
mosphere or from friction, especially when different metals are
concerned.
A rod of wood, generally of alder and about two feet long, was
put between the centres, and rechiced to a cylinder by a rounder
or witchet, attached to a slide running on the bar ; the slide with
the inclined knife was then applied, and the angle of the knife was
gradually varied by adjusting screws, until several screws made
in succession, were found to agree with some fixed measure. The
experiment was then repeated with the same angle, upon cylinders
of the same diameter, of tin, brass, and other comparatively soft
metals, and hundreds, or it might almost be said, thousands of
screws were thus made.
From amongst these screws were selected those which, on trial
in the lathe, were found to be most nearly true in their angle, or
to have a quiescent gliding motion ; and which would also best
endure a strict examination as to their pitch or intervals, both with
the rule and compasses, and also when two were placed side by
side, and their respective threads were compared, as the divisions
on two equal scales.
The most favorable screw having been selected, it was employed
as a guide-screw, in a simple apparatus which consisted of two
triangular bars fixed level, parallel, and about one foot asunder, in
appropriate standards with two apertures ; the one bar carried the
mandrel and popit-heads as in the ordinary bar lathe. The slide
rest embraced both bars, and was traversed thereupon by the
guide-screw placed about midway between the bars; the guide
screw and mandrel were generally connected by three wheels, or
else by two or four, when the guide and copy were required to
have the reverse direction. The mandrel was not usually driven
by a pulley and cord ; but on the extremity of the mandrel was
fixed a light wheel, with one arm serving as a winch handle for
rapid motion in running back ; and six or eight radial arms (after
the manner of the steering wheels of large vessels), by which the
mandrel and the screw were slowly handed round during the cut.
In a subsequent and stronger machine the bar carrying the man-
drel stood lower than the other, to admit of larger change wheels
upon it, and the same driving gear was retained. And in another
structure of the screw-cutting lathe, the triangular bar was placed
for the luthe heads in the centre, whilst a large and wide slide-
plate, moving between chamfer bars attached to the framing, car-
ried the sliding rest for the tool ; in this last machine, the mandrel
was driven by steam-power, and the retrograde motion had about
double the velocity of that used in cutting the screw.
The relations between the guide-screw and the copy were varied
in all possible ways : the guide was changed end for end, or dif-
ferent parts of it were successively used; sonietimes, also, two
guide-screws were yoked together with three equal wheels, their
nuts being connected by a bar jointed to each, and the centre of
SCREW-CUTTING TOOLS. 465
this link. (whose motion thus became the mean of that of the
guides) was made to traverse the tool. Steel screws were also cut,
and converted into original taps, from which dies were made, to be
themselves used in correcting the minor errors, and render the
screws in all respects as equable as possible. In fact, every
scheme that he could devise, which appeared likely to benefit the
result, was carefully tried, in order to perfect to the utmost, the
helical character and equality of subdivision of the screw.
The change of the thousandth part of the total length, was
therefore given to the tool as a supplementary motion, which might
be added to, or subtracted from, the total traverse of the tool, in
the mode explained by the diagram, Fig. 507, in which all details
of construction are purposely omitted. The copy C, and the guide-
screw G, are supposed to be connected by equal wheels in the
usual manner ; the guide-screw carries the axis of the bent lever,
whose arms are as 10 to 1, and which moves in a horizontal plane ;
the short arm carries the tool, the long arm is jointed to a saddle
which slides upon a triangular bar i i.
In point of fact, the tool was mounted upon the upper of two
longitudinal and parallel slides, which were collectively traversed
by the guide-screw G. In the lower slide was fixed the axis or
fulcrum of the bent lever, the short arm of which was connected
by a link with the upper slide, so that the compensating motion
was given to the upper slide relatively to the lower
Fig. 507.
The triangular bar i i, when placed exactly parallel with the path
of the tool, would produce no movement on the same, and C, and
G, would be exactly alike; but if i i were placed out of the paral-
lelism one inch in the whole length, the tool, during its traverse to
the left by the guide-screw G, would be moved to the right by the
shifting of the bent lever, one-tenth of the displacement of the bar,
or one-tenth of an inch.
Therefore, whilst the guide-screw G, from being coarser than
required, moved the principal slide the one-thousandth part of the
total length in excess ; the bent lever and inclined straight bar i i,
pulled back the upper or compensating slide, the one-thousandth
part, or the quantity in excess ; making the absolute traverse of the
tool exactly seven feet, or the length required for the new screw C,
instead of seven feet and one-sixteenth of an inch, the length of G.
To have lengthened the traverse of the tool, the bar % i must have
been inclined the reverse way ; in other words, the path of the tool
30
466 THE PRACTICAL METAL- WORKER'S ASSISTANT.
is in the diagram the difference of the two motions ; in the reverse
inclination, its path would be the sum of the two motions, and i i
being a straight line, the correction would be evenly distributed at
every part of the length.
Other experimentalists preferred, however, the method of the
chain, or flexible band, for traversing the tool the exact quantity ;
because the reduction of a diameter of the pulley or drum, afforded
a very ready means of adjustment for total length; and all the
wheels of the mechanism being individually as perfect as they could
be made, a near approach to general perfection was naturally antic-
ipated on the first trial. This mode, however, is subject to the
error introduced by the elasticity or elongation of the chain or
band, and which is at the maximum when the greatest length of
chain is uncoiled from the barrel.
About the year 1820, Mr. Clement put in practice a peculiar
mode for originating the guide-screw of his screw-lathe, the steps
of which plan will be now described.
1. He procured from Scotland some hand-screw tools cut over a
hob with concentric grooves ; and to prevent the ridges or points
of the screw tools from being cut square across the end, the rest
was inclined to compensate for the want of angle in the hob or
cutter.
2. A brass screw was struck by hand, or chased with the tool 1,
3. The screw 2, was fixed at the back of a traversing mandrel,
and clipped between two pieces of wood or dies to serve as a guide,
whilst,
4. A more perfect guide-screw was cut with a fixed tool, and
substituted on the mandrel for 3 ; as Mr. Clement considered the
movement derived from the opposite sides of the one screw, became
the mean of the two sides, and corrected any irregularities of angle,
or of drunkenness.
5. A large and a small master-tap m, Fig. 508, were cut on the
traversing mandrel with a fixed tool, the threads were about an
inch long and situated in the middle of a shaft eight or ten inches
long ; the small master-tap was of the same diameter as the finished
screw, the large master-tap measured at the bottom of the thread
t he same as the blank cylinder to be screwed. The master-taps m,
were used in cutting up the rectangular dies required in the apparatus
shown in Fig. 508, and now to be described.
6. On the parallel bed of a lathe were fitted two standards or
collar-heads h h', intended to receive the pivots of the screw to be
cut, on the extremity of which was placed a winch handle, or some-
times an intermediate socket was interposed between the screw ana
the winch, to carry the latter to the end of the bed. The bed had
also an accurate slide plate s sr, running freely upon it, the slide
plate had two tails which passed beside the head h', and at the
other end, a projection through which was made a transverse rec-
tangular mortise for the dies, the one end of the mortise is shown
by the removal of the front die d, and the back die d' is seen in its
SCREW- CUTTING TOOLS,
467
proper situation ; one extremity of each die was cut from the large
master tap m, and the other from the small. The clamp or shackle
c c', was used to close the two dies upon the screw simultaneously ;
it is shown out of its true position in order that the dies and mortise
may be seen, but when in use the shackle would be shifted to the
right, so as to embrace the dies d d-. The plain extremity c' rested
against the back die, whilst the screw c bore against the front die,
through the intervention of the washer loosely attached to the
clamp to save the teeth from injury ; the pressure screw c had a
graduated head and an index, to denote how much the dies were
closed.
1 — i*# ' 9
"7. A cylinder about two feet long, prepared for the screw, was
placed between the heads h hf, and the large dies, whose inner
edges were of the same diameter as the cylinder, were closed upon
it moderately tight, and the screw was turned round with the winch,
to trace a thread from end to end ; this ^ as repeated a few times,
the dies being slightly closed between each trip,
8. A screw-tool was next fixed on the slide 5 s', in a chamfer
slide 1 1', with appropriate adjusting screws, so as to follow the dies
and remove a shaving, much the same as in turning. The dies
having arrived at one end of the screw, the same screw tool or
a second tool was placed on the opposite side of the side-plate so
as to cut during the return movement. With the progress of the
screw the screw-tool was applied at a variety of distances from the
pair of dies, as well as on opposite sides of the screw, so that the
metal was cut out by the tool, and the dies were used almost alone
to guide the traverse. Of course the dies were closed between
each trip, and when the screw was about half cut up the small dies
were substituted for the large ones used at the commencement of
the process.
9. The screw thus made, which was intended for a slide-rest,
was found to be very uniform in its thread, and it was used for
some time for the ordinary purposes of turning. When, however,
it was required to be used for cutting other screws, it was found
objectionable that its rate was nearly nine, whereas it was required
to^iave eight threads per inch. It was then used in cutting a new
guide-screw by means of a pair of change wheels of 50 and 56
468
THE PRACTICAL METAL-WORKER'S ASSISTANT.
teeth, which upon calculation were found to effect the conversion
with sufficient precision.
10. From 9, the screw of 24 inches in length, one of 8 feet in
length was obtained. The thread was cut one-third of its depth,
with the wheels, successive portions being operated upon and the
tool being carefully adjusted to the termination of the part pre-
viously cut. The general truth of the entire length was given by
Fig. 509.
a repetition of the tedious mode of correction represented in the
figure, with the dies and tool applied upon a bearer rather exceed-
ing the full length of the screw.
Fig. 510.
Although the processes 7 and 8 will produce a most uniform
1 screw, Mr. Clement attaches little importance to the use of the dies
SCREW-CUTTING TOOLS.
469
Fig. 511.
and guide-frame alone when several screws are wanted strictly of
the same length. Of some few thus made as nearly as possible under
equal circumstances two screws were found very nearly to agree,
and a third was above a tenth of an inch
longer in ten inches. This difference he
thinks to have arisen in marking out the
threads, from a little variation in the fric-
tion of the slide, or a difference in the
first penetration of the dies.
The friction of the slide, when sufficient
to cause any retardation, he considers to
produce a constant and accumulative ef-
fect ; first, as it were, reducing the screw
of 15 threads per inch, say to the fineness
of 15 J, then acting upon that of 15J, re-
ducing it to 15 J, and so on ; and that to
such an extent, as occasionally to place
the screw entirely beyond the correctional
process. This cannot be the case when
the thread is first marked out with the
change-wheels instead of the dies.
One very important application of the
screw is to the graduation of mathe-
matical scales. The screw is then em-
ployed to move a platform, which slides
very freely and carries the scale to be graduated ; and the swing
frame, for the knife or diamond point, is attached to some fixed
part of the framing of the machine. Supposing the screw to be
absolutely perfect, and to have fifty threads per inch, successive
movements of fifty revolutions would move the platform and grad-
uate the scale exactly into true inches ; but on close examination
some of the graduations will be found to exceed, and others to fall
short of, the true inch.
The scales assume, of course, the relative degree of accuracy of
the screw employed. No test is more severe ; and when these scales
are examined by means of two microscopes under a magnifying
power of ten or twenty times, the most minute errors become
abundantly obvious from the divisions of the scales failing to in-
tersect the cross wires of the instrument ; the result clearly indi-
cates corresponding irregularities in the coarseness of the screw at
the respective parts of its length. An accustomed eye can thus
detect, with the microscope, differences not exceeding the one thirty-
thousandth part of an inch, the twenty-five-thousandth part being
comparatively of easy observation.
Figs. 509 and 512 show a large chucking and reaming lathe
built at Lowell, Massachusetts.
Figs. 510 and 511 show a chucking and reaming lathe manu-
factured at Lowell. This instrument is geared with a rest for
holding drills and reamers moved by a toothed rack, backhead
470
THE PRACTICAL METAL- WORKER'S ASSISTANT.
stock, adjustable sideways, cast-iron cone-pulleys, gun metal bear-
ings, and cast-steel spindle.
Pig. 512.
Fig. 513 is an engine lathe manufactured at the Lowell Machine
Shop, Lowell, Massachusetts. Its swing is 50 inches over the sills,
and 32 over the rest.
Fig. 513.
The bed of this lathe is cast in one piece, the feed motion is
carried by a screw, the tool rest held down by gibs under the slides,
and moved on a toothed rack and pinion by hand.
SCREW THREADS CONSIDERED IN KESPECT TO THEIR PROPOR-
TIONS, FORMS, AND GENERAL CHARACTERS. — The proportions given
to screws employed for attaching together the different parts of
works are in nearly every case arbitrary, or, in other words, they
are determined almost by experience alone rather than by rule,
and with little or no aid from calculation, as will be shown.
In addition to the ordinary binding screws, which, although arbi-
trary, assume proportions not far distant from a general average,
manv screws, either much coarser or finer than usual, are continu-
SCREW-CUTTING TOOLS. 471
r^Jv required for specific purposes; as are likewise other screws of
some definite number of turns per inch — as 2, 10, 12, 20, etc.— in
order to effect some adjustment or movement having an immediate
reference to ordinary lineal measure. But all these must be con-
sidered as still more distant than common binding screws from any
fixed proportions, and not to be amenable to any rules beyond those
of general expediency.
Neither the pitch, diameter, nor depth of thread, can be adopted
as the basis from which to calculate the two other measures, on
account of the different modes in which the three influence the
effectiveness of the screw ; nor can the proportions suitable to the
ordinary f inch binding screw be doubled for the 1J inch screw, or
"halved for that of f inch, as every diameter requires its individual
scale to be determined in great measure by experiment in order to
produce something like a mean proportion between the dissimilar
conditions, which will be separately explained in various points of
view.
The reasons for the uncertainty of measure in the various fixing
screws required in the constructive arts are sufficiently manifest ;
as first, the force or strain to which a screw is exposed, either in the
act of fixing or in the office it has afterward to perform, can rarely
be told by calculation ; and secondly, a knowledge of the strain the
screw itself will safely endure without breaking in two, or without
drawing out of the' nut, is equally difficult of attainment; nor
thirdly, can the deduction for friction be truly made from that
force the screw should otherwise possess from its angle or pitch
when viewed as a mechanical power, or as a continuous circular
wedge.
The force required in the fixing of screws takes a very wide
range, and is faintly indicative of the strain exerted on each. The
watchmaker, in fixing his binding screws, employs with great
delicacy a screw-driver the handle of which is smaller than an
ordinary drawing pencil ; while for screws, say of five inches dia-
meter, a lever of six or seven feet long must be employed by the
engineer, with the united exertions of as many men. But in
neither case do we arrive at any available conclusion, as to the pre-
cise force exerted upon, or by each screw; nor of the greatest strain
that each will safely endure.
The absolute measures of the strength of any individual screw
being therefore nearly or quite unattainable, all that can be done
to assist the judgment, is to explain the relative or comparative mea-
sures of strength in different screws, as determined by the three
conditions which occur in every screw; whether it be right or left-
handed, of single or of multiplex thread, or of any section what-
ever ; and which three conditions follow different laws, and con-
jointly, yet oppositely determine the fitness of the screw for its par-
ticular purpose, and therefore tend to perplex the choice.
The three relative or comparative measures of strength in different
screws are : first, the mechanical power of the thread, which is de-
472
THE PRACTICAL METAL-WORKERS ASSISTANT.
rived from its pitch ; secondly, the cohesive strength of the loU. which
is derived f™m it* transverse section; thirdly, the cohesive strength
of the hold, which is derived from the interplacement of the threads
of the screw and nut.
These conditions will be first considered, principally as regards
ordinary binding screws, and screw bolts and nuts, of angular
threads, and which indeed constitute by far the largest number of
all the screws employed; screws of angular and square threads will
be then compared.
The comparative sections, Figs. 514 to 517, represent screws of
the same diameters, and in all of which the depth of the thread is
equal to the width of the groove; Figs. 515 and 517 show the ordi-
d\nary proportions of f inch angular and square thread screws ;
514 and 516 are respectively as fine and as coarse again as 515.
Figs. 514
515
516
VWWWVA/WW
Various measures of the screws which require little further ex-
planation are subjoined in a tabular form; and the relative degrees
of strength possessed by each screw under three different points of
view, are added.
MEASURES AND RELATIVE STRENGTHS OP THE SCREWS.
Fig.
514.
Fig.
515.
Fig.
516.
Fig.
517.
External diameters in hundredths of an inch . . . •
Internal diameters in hundredths of an inch . . . •
Number of threads per inch, or rates of the screws . •
Depths and widths of the threads in hundredths . .
Angles of the threads on the external diameters* . .
Angles of the threads on the internal diameters* . .
Relative mechanical powers of the threads . . . .
Relative cohesive strengths of the bolts . . . .
.75
.65
.20
.05
1°16'
1°28'
20
4
.75
.55
10.
.10
2°33'
3°28'
10
3
.75
.35
5.
.20
5° 5'
10°47'
5
1
.75
.55
5.
.10
5° 5'
6°55'
5
3
Relative cohesive strengths of hold" of the screws .
Relative cohesive .strengths of hold of the nuts . . .
65
75
55
75
35
75
27*
37|
Square thread screws, have about twice the pitch of angular
threads of similar diameters, and Fig. 517 estimated in the same
manner as the angular, will stand by comparison as follows. The
* The angles of the threads of screws are calculated trigonometrically, the
circumference of the bolt being considered as the base of a right-angled triangle,
and the pitch as the height of the same.
The author has adopted the following mode, which will be found to require
the fewest figures ; namely, to divide the pitch by the circumference, and to
seek the product in the table of tangents ; decimal numbers are to be used,
and it is sufficiently near to consider the circumference as exactly three timei
the diameter.
SCREW-CUTTING TOOLS. 473
square thread, Fig. 517, will be found to be equal in power to
Fig. 516, the pitch being alike in each. In strength of bolt to be
equal to Fig. 515, their transverse areas being alike. And in
strength of hold, to possess the half of that of Fig. 515, because the
square thread will from necessity break through the bottom of the
threads, or an interrupted line exactly like the dotted line in Fig.
516, that denotes just half the area or extent of base, of the thread
of Fig. 515; which latter covers the entire surface of the contained
cylinder, and not the half only.
The mechanical power of the thread is derived from its pitch. The
power, or the force of compression, is directly as the number of
threads per inch, or as the rate; so that neglecting the friction in
both cases, Fig. 514 grasps with four times the power of Fig. 516,
because its wedge or angle is four times as acute.
When, however, the angle is very great, as in the screws of fly-
presses, which sometimes exceed the obliquity of 45 degrees, the
screw will not retain its grasp at all; neither will a wedge of 45
degrees stick fast in a cleft. Such coarse screws act by impact ;
they give a violent blow on the die from the momentum of the fly
(namely, the loaded lever, or the wheel fixed on the press-screw)
being suddenly arrested ; they do not wedge fast, but on the con-
trary, the reaction upwards unwinds and raises the screw for the
succeeding stroke of the fly-press.
Binding screws which are disproportionately coarse, from lean-
ing towards this condition, and also from presenting less surface-
friction, are liable to become loosened if exposed to a jarring ac-
tion. But when, on the contrary, the pitch is very fine, or the
wedge is very acute, the surface friction against the thread of the
screw is such, as occasionally to prevent their separation when the
screw-bolt has remained long in the hole or nut, from the adhesion
caused by the thickening of the oil, or by a slight formation of
rust.
The cohesive strength of the bolt is derived from its transverse section.
The screw may be thus compared with a cylindrical rod of the
some diameter as the bottom of the thread, and employed in sus-
taining a load ; that is, neglecting torsion, which if in excess may
twist the screw in two. The relative strengths are represented by
the squares of the smaller diameters : in the screws of 20, 10, and
5 angular threads, the smaller diameters are 65, 55, and 35 ; the
squares of these numbers are 4225, 3025, and 1225, which may be
expressed in round numbers as 4, 3, 1 ; and, therefore, the coarsest
screw, Fig. 516, has transversely only one-fourth the area, and conse-
For the external angle of Fig. 516 say .20+2.25^.0888, and this quotient
by Huttou's Tables gives 5 deg. 5 min.
For the internal angle of Fig. 514 say .054-1.95—0.2564, and by Button's
Tables, 1 deg. 28 min.
In this method the pitch is considered as the tangent to the angle, and the
division effects the change of the two sides of the given right-angled triangle,
for two others, the larger of which is 1 or unity, for the convenience of using
the tables.
474 THE PRACTICAL METAL-WORKER'S ASSISTANT.
quently one-fourth tbe strength of the nnest, represented in the
three diagrams.
The, cohesive strength of the hold is derived from the helical ridge of
the external screw, being situated within the helical groove of the inter-
nal screw. The two helices become locked together with a degree
of firmness, approaching to that by means of which the different
particles of solid bodies are united in a mass ; as one or both of
the ridges must be in a great measure torn off in the removal of
the screw, unless it be unwound or twisted oat.
A slight difference in the diameter or the section of a screw and
nut, is less objectionable than any variation in the coarseness or
pitch ; as the latter difference, even /when very minute, will pre-
vent the screw from entering the hole, unless the screw is made
considerably smaller than it ought to be, and even then it will
bear very imperfectly, or only on a few places of the nut.
To attempt to alter a screwed hole by the use of a tap of a dif-
ferent pitch, is equally fatal, as will be seen by the annexed dia-
Fig. 518.
/\/wvy/
gram, Fig. 518. For instance, the upper line a, contains exactly 4
threads per inch, and the middle line or b, has 4J threads ; they
only agree at distant intervals. The lowest line c, shows that which
would result from forcing a tap of 4 threads such as a into a hole
which had been previously tapped with the 4J thread screw b, the
threads would be said to cross, and would nearly destroy each
other ; the same result would of course occur from employing 4 or
5 thread dies on a screw of 4J threads per inch.
Therefore, unless the screw tackle exactly agree in pitch with
the previous thread, it is needful to remove every vestige of the
former thread from the screw or hole ; otherwise the result drawn
at c, must ensue in a degree proportionate to the difference of the
threads, and a large portion of the bearing surface, and conse-
quently, of the strength and durability of the contact, would each
be lost. Some idea may thence be formed of the real and irreme-
diable drawback frequently experienced from the dissimilarity of
screwing apparatus ; nearly to agree will not suffice, as the pitch
should be identical.
The nut of a }-inch screw bolt is usually } inch thick, as it is
SCREW-CUTTING TOOLS. 475
considered that when the threads are in good contact, and collec-
tively equal to the diameter of the bolt, that the mutual hold of
the threads exceeds the strength either of the bolt or nut ; and
therefore that the bolt is more likely to break in two, or the nut
to burst open, rather than allow the bolt to draw out of the hole,
from the thread stripping off.
When screws fit into holes tapped directly into the castings or
other parts of mechanism, it is usual to allow still more threads to
be in contact, even to the extent of two or more times the diame-
ter of the screw, so as to leave the preponderance of strength
greatly in favor of the hold ; that the screw, which is the part
more easily renewed, may be nearly certain to break in two, rather
than damage the castings by tearing out the thread from the
tapped hole.
Should the internal and external screws be made in the same
material, that is both of wood, brass or iron, the nut or internal
screw is somewhat the stronger of the two. For example, in the
screw Fig. 515, the base of the thread is a continuous angular
ridge, which occupies the whole of the cylindrical surface repre-
sented by the dotted line. Therefore the force required to strip
off the thread from the bolt, is nearly that required to punch a
cylindrical hole of the same diameter and length as the bottom of
the thread ; for in either case the whole of the cylindrical surface
has to be stripped or thrust off laterally, in a manner resembling
the slow, quiet action of the punching or shearing engine.
But the base of the thread in the nut, is equal to the cylindrical
surface measured at the top of the bolt, and consequently, the mate
rials being the same, and the length the same, considering the
strength of the nut for Fig. 515 to be 75, the strength of the bolt
would be only 55, or they would be respectively as the diame-
ters of the top and bottom of the thread ; although when the bolt
protrudes through the nut, the thread of the bolt derives a slight
additional strength, from the threads situated beyond the nut, and
which serve as an abutment.
It is however probable that the angular thread will not strip off
at the base of the threads, either in the screw or nut, but will break
through a line somewhere between the top and bottom : but these
results will occur alike in all, and will not therefore materially
alter the relation of strength above assumed.
Comparing Figs. 514, 515, and 516, upon the supposition that
the bolts and nuts exactly fit or correspond, the strengths of the
three nuts are alike, or as 75, and those of the bolts are as 65, 55,
and 35, and therefore the advantage of hold lies with the bolt
of finest thread ; as the finer the thread, the more nearly do the
bolt and nut approach to equality of diameter and strength.
Supposing, however, for the purpose of explanation, that instead
of the screws and nuts being carefully fitted, the screws are each
one-tenth of an inch smaller than the diameters of the respective
taps employed in cutting the three nuts ; Fig. 514 would draw
476 THE PRACTICAL METAL-WORKERS ASSISTANT.
entirely out without holding at all; the penetration and hold of
Fig. 515 would be reduced to half its proper quantity ; and that
of Fig. 516 to three-fourths; and the last two screws would strip at
a line more or less elevated above the base of the thread, and
therefore the more easily than if the diameters exactly agreed.
The supposed error, although monstrous and excessive, shows
that the finer the thread, the greater also should be the accuracy of
contact of such screws ; and it also shows the impolicy of employ-
ing fine threads in those situations where they will be subjected to
frequent screwing and unscrewing, and also to much strain. As
although when they fit equally well, fine threads are somewhat
more powerful than coarse, in hold as well as in mechanical
power ; the fine are also more subject to wear, and they receive
from such wear, a greater and more rapid depreciation of strength,
than threads of the ordinary degrees of coarseness.
In a screw of the same diameter and pitch, the ultimate strength
is diminished in a twofold manner by the increase of the depth of
the thread ; first it diminishes the traverse area of the bolt, which
is therefore more disposed to break in two ; and secondly, it
diminishes the individual strength of each thread, which becomes
a more lofty triangle erected on the same base, and is therefore
more exposed to fracture or to be stripped off.
But the durability of machinery is in nearly every case increased
by the enlargement of the bearing surfaces, and therefore as the
thread of increased depth presents more surface-bearing, the deep
screw has constantly greater durability against the friction or wear,
arising from the act of screwing and unscrewing. The durability
of the screw becomes in truth a fourth condition, to be borne in
mind collectively with those before named.
It frequently happens that the diameters of screwed works are
so considerable, that they can neither break nor burst after the
manner of bolts and nuts ; and if such large works yield to the
pressures applied, the threads must be the part sacrificed. If the
materials are crystalline, the thread crumbles away, but in those
which are malleable and ductile, the thread, instead of stripping
off as a wire, sometimes bends until the resisting side presents a
perpendicular face, then overhangs, and ultimately curls over:
this disposition is also shown in the abrasive wear of the screw
before it yields.
Comparing the square with the angular thread in regard to fric-
tion, the square has less friction, because the angular edges of the
screw and nut, mutually thrust themselves into the opposite angular
grooves in the manner of the wedge. The square thread has also
the advantage of presenting a more direct thrust than the angular,
because in each case the resistance is at right angles to the side of
the thread, and therefore in the square thread the resistance is very
nearly in the line of its axis, whereas in the angular it is much
more oblique.
From these reasons, the square thread is commonly selected for
SCREW-CUTTING TOOLS.
477
presses,- and for regulating screws, especially those in which
rapidity of pitch, combined with strength, is essential; but as
regards the ordinary attachments in machinery, the grasp of the
angular thread is more powerful, from its pitch being generally
about as fine again, and, as before explained, angular screws and
nuts are somewhat more easily fitted together.
The force exerted in bursting open a nut, depends on the angle
formed by the sides of the thread, when the latter is considered as
part of a cone, or as a wedge employed in splitting timber. For
instance, in the square thread screw, the thread forms a line at
right angles to the axis, and which is dotted in the figure 519 ; it
is not therefore a cone, but simply compresses the nut, or attempts
to force the metal before it. In the deep thread, Fig. 520, the
wedge is obtuse, and exerts much less bursting effort than the
Figs. 519
520
I
acute cone represented in the shallow thread screw, Fig. 521 ;
therefore, the shallower the angular thread, the more acute the
cone, and the greater the strain it throws upon the nut. The
transverse measure' of nuts, whether they are square or hexagonal,
is usually about twice the diameter of the bolt, as represented in
the figures, and this in general suffices to withstand the bursting
effort of the bolt.
In the table of dimensions of nuts, in " Byrne's Engineer's
Pocket Companion," the traverse measures decrease in the larger
nuts ; the breadth of a nut for a J inch bolt is stated as 1 inch,
that for a 2J inch bolt as four inches.
Those nuts, however, which are not used for grasping, but for
the regulating screws of slides and general machinery, are made
much thicker, so as to occupy as much of the length of the screw
as two, three, or more times its diameter. This greatly increases
their surface-contact and durability.
Should it be required to be able to compensate the nut, or to re-
adapt it to the lessened size of the screw when both have been
worn, the nut is made in two parts and compressed by screws, or it
is made elastic so as to press upon the screw. The nuts for angular
threads are divided diametrically and reunited by two or more
screws, as in Fig. 522 — in fact, like the semi- circular bearings of
ordinary shafts ; as then by filing a little of the metal away from
478
THE PRACTICAL METAL-WORKER^ ASSISTANT.
between the two halves of the nut, they may be closed upon the
angular ridges of the thread.
The nuts of square threads by a similar treatment would, on
being closed, fit accurately upon the outer or cylindrical surface of
the square thread screw ; but the lateral contact would not be re-
stored; these nuts are, therefore, divided transversely, as shown in
Fig. 523, or they are made as two detached nuts placed in contact.
When, therefore, a small quantity is removed from between them
with the file, or that they are separated by one or more thicknesses
of paper, the one-half of the nut bears on the right hand side of
the square worm, the other on the left.
Figs. 522
525
Either of these methods removes the "end play" or the " loss of
* by which expression is meant that partial revolution to and
fro which may be given to a worn screw without producing any
movement or traverse in the slide upon which the screw acts. It is
usual, before cutting the nuts in the lathe or with screw traps, to
divide the nuts, and to reunite <them with soft solder, or it is better
to hold them together with the permanent screws whilst cutting the
thread.
But the screws of slides are very apt to become most worn in
Vhe middle of their length, or at the one end. leaving the other
oarts nearly of their original size. It is then best to replace them
oy new screws, as the former method of adjusting the nuts cannot
oe used ; although recourse may occasionally be had to some of
die various methods of springing, or the elastic contrivances com-
monly employed in delicate mathematical and astronomical instru-
ments. Although these should be perfectly free from shake or
mcertainty of motion, they do not in general require the firm,
massive, unyielding structure of engineering works and machinery.
Two kinds of the elastic nuts alone are shown ; in Fig. 524 the
raw-cut extends throughout the length of the nut, but sometimes a
portion in the middle is left uncut; the-nut is usually a little set-in,
or bent inwards with the hammer, so as to press upon the screw.
In Fig. 525 the two pieces a and b bear against opposito sides of tne
SCKEW-CUTTING TOOLS. 479
threads, and b only is fixed to the slide as in Fig. 523 ; the correc-
tion is now accomplished by interposing loosely around the screw
and between the halves of the nut, a spiral spring sufficiently strong
to overcome the friction of the slide upon the fittings ; the same
contrivance is variously modified, sometimes two or four spiral
springs are placed in cavities parallel with the screw.
The slide resists firmly any pressure from a to b, as the fixed half
of the nut lies firmly against the side of the thread presented in that
direction, but the pressure from b to a is sustained alone by the
spiral spring; when, therefore, the pressure exceeds the strength
of the spring, the slide nevertheless moves endways to the extent
of the misfit in the piece b, and which, but for the spring, would
allow the slide to shake endways. In absolute effect the contrivance
is equivalent to a single nut such as b alone, which, although pos-
sessing end play if pulled towards b by a string and weight, would
always keep in contact with the one side of the worm, unless the
resistance were sufficient to raise the weight. The method is there-
fore only suited to works requiring delicacy rather than strength,
and the spring, if excessively strong, would constantly wear the
two halves of the nut with injudicious friction and haste.
The several threads represented in Figs. 526 to 538 may be con-
sidered to be departures from the angular thread Fig. 526 and the
square thread Fig. 535, which are by far the most common.
The choice of section is collectively governed: First, by the
facility of construction, in which the plain angular thread excels.
Secondly, by the best resistance to strain, which is obtained in the
square thread. Thirdly, by the near equality of strength in the
internal and external screw. For similar materials the space and
thread should be symmetrical, as in the square thread, and in Figs.
526 to 530, which screws are proper for metal works generally ;
whereas in dissimilar materials the harder of the two should have
the slighter thread, as in the iron screws, Figs. 531 to 534, intended
to be screwed into wood ; the substance of the screw is supposed
'to be below the line, and the head to the right hand. Fourthly, by
the resistance to accidental violence, either to the screws, or to the
screwing tools, which is best obtained by the rejection of sharp
angles or edges, as in the several rounded threads. This fourfold
choice of section, like every other feature of the screw, is also
mainly determined by experience alone.
Fig. 526, in which the angle is about 60 degrees, is used for most
of the screws made in wood, whether in the screw-box or the turn-
ing lathe ; and also for a very large proportion of the screw bolts
of ordinary mechanism. Sometimes the points of the screw tool
measure nearly 90 degrees, as in the shallow thread, Fig. 527, used
for the thin tubes of telescopes; or at other times they only
measure 45 degrees, as in the very deep thread, Fig. 528, used for
some mathematical and other instruments. The angles represented
may be considered as nearly the extremes.
In originating accurate screws, the angular thread is always
480
THE PRACTICAL METAL- WORKER'S ASSISTANT.
Figs.
Sections derived from the
ANGULAR THREAD.
526 A/VVWXVWV
528
529
A/WVYVWW
530 AAAA/VVVVVV
531 JUUUVJUUUVJUU
532 AAAAAAAAAA/
533
531
selected, because the figure
of the thread is still main
tained, whether the tool cut
on one or on both sides of
the thread, in the course of
the correctional process.
Fig. 529 is the angular
thread in which the ridges
are more or less truncated to
increase the strength of the
bolt ; it may be viewed as a
compound of the square and
angular thread.
Fig. 530 is the angular
thread in which the tops and
bottoms are rounded ; it is
much used in engineering
works, and is frequently
called a round thread.
In Fig. 531 the thread is
more acute, and truncated
only at the bottom of the
screw. This is used for
joinery-work, and greatly in-
creases the hold upon the
wood. Fig. 532 is obviously
derived from Fig. 531, and is
used for the same purpose.
In Fig. 533, which is also
a screw for wood, the face
that sustains the hold is rec-
tangular, as in the square
thread — the other is beveled.
Fig. 534 is the form of the
patent wood screw sometimes
called the German screw. It
is hollowed, to throw the advantage of bulk in favor of the softer
material, or the wood, the head of which is supposed to be on
the right hand. In the last four figures, the substance of the
screw is imagined to be situated below the line, and that of the
wood above.
The screws which are inserted into wood are generally made
taper, and not cylindrical, in order that they may cut their own
nut or internal thread. Some of them are pointed, so as to pene-
trate without any previous hole being made — they merely thrust
the fibres of wood on one side. Screws hold the most strongly
in wood when inserted horizontally .as compared with the po-
sition in which the tree grew, and least strongly in the vertical
position. ,
Sections derived from the
SQUARE THREAD.
535 -
536
537
538
\JlTLAJ\r
%/xrvxrLn
SCREW-CUTTING TOOLS. 481
/
Fig. 53.5 represents the ordinary square thread screw. The
space and thread are mostly of equal width, and the depth is either
equal to the width, or a trifle more, say one-sixth.
Fig. 536 is a departure from Fig. 535, and has been made for
presses ; and Fig, 537 has obviously grown out of the last from the
obliteration of the angles. Various proportions intermediate be-
tween Figs 537 and 530 are used for round threads.
Tn some cases where the screw is required to be rapid, one
single shallow groove is made of angular, square, or circular sec-
tion, leaving much of the original cylinder standing, as in Fig. 538.
For very slight purposes a pin only is fitted to the groove to serve as
the nut. Should the resistance be greater, many pins, or a comb
may be employed, and this was the earliest form of nut; otherwise
a screwed nut may be used with a single thread. But when the
greatest resistance is required the surface bearing of the nut is ex-
tended by making the thread double, triple, etc., by cutting one or
more intermediate grooves and a counterpart nut.
The nuts or boxes of very coarse screws for presses are now
mostly cut in the lathe, although, when the screwing tools were
less perfectly understood, the nuts were frequently cast. Some-
times lead, or alloys of similar fusibility, were poured in betwixt
the screw and the framework of the machinery ; but for nuts of
brass and gun-metal, sand moulds were formed. The screw was
always warmed to avoid chilling the metal ; and for brass, it was
sometimes heated to redness and allowed to cool, so as slightly to
oxidize the surface and lessen the disposition to a union or natural
soldering of the screw and nut. It was commonly necessary to
stretch the brass by an external hammering, to counteract the
shrinkage of the metal in the act of cooling, and to assist in releas-
ing from the screw the nut cast upon it in this manner. The mode
is by no means desirable, as the screw is exposed to being bent
from the rough treatment, and to being ground by particles of
sand adhering to the brass.
The tangent screws used for screw wheels have mostly angular
or truncated angular threads, Fig. 529, as screws absolutely square
cannot be fitted with good contact and freedom from shake be-
tween the thread and teeth ; and probably the same rules by
which the teeth of ordinary wheels and racks are reciprocally set
out, should be also applied to the delineation of the teeth of worm
wheels, and the threads or teeth of their appropriate screws.
Tangent screws are occasionally double, triple, or quadruple, in
order that 2, 3, or 4 teeth of the wheel may be moved during each
revolution of the screw. In the Piedmont silk-mills, this principle
is carried to the extreme, as the screw and wheel become alike,
and revolve turn for turn ; the teeth, supposing them to be 20, are
then identical with those of a 20 thread screw, the angular coils of
which cross the axis at the angle of 45°, that is, when the shafts
lie at right angles to each other ; other proportions and angles may
be adopted. In realitv they fulfil the office of bevel wheels, or
31
482 THE PRACTICAL METAL-WORKER' 3 ASSISTANT.
rather of skew-bevel wheels, in which latter also, the axes, from
being in different planes, may cross each other ; so that the skew-
bevel wheels may be in the centre of long shafts, but which cannot
be the case in ordinary bevel wheels, the teeth of which lie in the
same plane as the axis of the wheel. The Piedmont wheels act
with a very reduced extent of bearing or contact surface, and a
considerable amount of the sliding action of screws, which is dis-
advantageous in the teeth of wheels, although inseparable from all
those with inclined teeth, and which are indeed more or less dis-
tant modifications of the screw.
When the obliquity of the teeth of worm wheels is small, it
gives a very smooth action, but. at the expense of friction ; but in
ordinary toothed wheels, the teeth are exactly square across or in
the plane of the axis, and the aim is to employ rolling contact,
with the greatest possible exclusion of sliding, from amongst the
teeth.
Having treated somewhat in detail the different forms of screws,
and the circumstances which adapt them to their several purposes,
I have now to consider some of the inconveniences which have
unavoidably arisen from the indefinite choice of proportions in
ordinary screws, and also some of the means that have been pro-
posed for their correction. The slight discussion of the more im-
portant of these topics will permit the introduction of various
additional points of information on this almost inexhaustible sub-
ject, the screw.
No inconvenience is felt from the dissimilarities of screws, so
long as the same screwing tools are always employed in effecting
repairs in, or additions to, the same works. But when it is con-
sidered, how small a difference in either of the measures will mar
the correspondence of the screw and nut ; and further, the very
arbitrary and accidental manner, in which the proportions of screw-
ing apparatus have been determined by a variety of individuals,
to suit their particular wants, and without any attempt at uniform-
ity of practice (sometimes, on the contrary, with an express de-
sire to be peculiar), it is perhaps some matter of surprise when the
screws made in different establishments properly agree. Indeed
their agreement can be hardly expected, unless they are derived
from the same source, and that some considerable pains are taken
not to depart from the respective proportions first adopted.
In a few isolated cases this inconvenience has been partially
remedied by common consent and adoption, as in the so-called air-
pump thread, which is pretty generally used by the makers of
pneumatic apparatus ; and to a certain degree also in some of the
screws used in gas-fittings and in gun-work. But the non-exis-
tence of any common standard or scale, enhances both the delay
and Expense of repairs in general mechanism, and leads to the
occasional necessity for making additional sizes of tools to match
particular works, however extensive the supply of screw apparatus.
The perplexity is felt in a degree especially severe and costly, as
SCREW-CUTTING TOOLS.
483
regards marine and locomotive engines, whicli from necessity, have
to be repaired in localities far distant from those in which they
were made ; and therefore require that the packet station, or rail-
way depot, should contain sets of screwing tackle, corresponding
with those used by every different manufacturer whose works
have to be dealt with ; otherwise, both the delay and expense are
from necessity aggravated.
Some engineers suggested that for steam machinery and for the
purpose of engineering in general, " an uniform system of screw
threads" should be adopted. The following table may be consid-
ered as a mean between the different kinds of threads used by the
leading engineers :
Table for Angular Thread Screws.
Diameters in inches ...
Noa. of threads to the inch .
Diameters in inches ...
Nos. of threads to the inch .
r:24 2? H'
U 3J3i
1*| 4 ! I
14 12111
i"|U U
9877
21
, 4| 5" 5i
Hi||2f|n
1||2"
"'«
5i 54|5| 6"
24|24
In selecting this scale, the following very judicious course was
adopted : An extensive collection was made of screw-bolts from
the principal workshops, and the average thread was carefully ob-
served for different diameters. The J inch, J inch, 1 and 1J inch,
were particularly selected, an$ taken as the fixed points of a scale
by which the intermediate sizes were regulated, avoiding small
fractional parts in the number of threads to the inch. The scale
was afterwards extended to 6 inches. The pitches thus obtained
for angular threads were as above :
Above the diameter of 1 inch the same pitch is used for two
sizes, to avoid small fractional parts. The proportion between the
pitch and the diameter varies throughout the entire scale.
Thus the pitch of the J inch screw is Jth of the diameter ; that
of the J inch Jth, of the 1 inch |th, of the 4 inches i^th, and of
the 6 inches 1*5 th.
The depth of the thread in the various specimens is then
alluded to. In this respect the variation was greater than in the
pitch. The angle made by the sides of the thread being taken as
an expression for the depth, the mean of the angle in 1 inch
screws was found to be about 55°, which was also nearly the mean
ia screws of different diameters. Hence it was adopted throughout
the scale, and a constant proportion was thus established between
the depth and the pitch of the thread. In calculating the former,
a deduction must be made for the quantity rounded off, amount-
ing to Jd of the whole depth, i. e. Jth from the top, and Jth from
the bottom of the thread. Making this deduction, the angle of
55° gives for the actual depth rather more than ?ths, and less than
f ds of the pitch.
As regards the smaller mechanism, made principally in brass
and steel, such as mathematical instruments and many others, the
484
THE PRACTICAL METAL-WORKER'S ASSISTANT.
screws in the above scale below half an inch diameter are admitted
to be too coarse ; and the acute angular threads which are not
rounded are decidedly to be preferred, from their greater delicacy
and durability, — that is, when their strengths are proportioned to
the resistances to which they are exposed. In these respects the
following table may be considered preferable :
Table for Small Screws of Fine Angular Threads.
Diameters in vulgar fractions of the inch . .
t
&l
T7S
*i
•|
tt
h
A
i
A
4
Diameters in hundredths of the inch nearly
.50
.47
.44
.41
.37
.34
.31
.28
.25
.22
.20
Number of threads to the inch
i rt
2.1
28
Jft
32
Diameters in hundredths of the inch ....
.18
.16
.14
.12
.10
.09
.08
-07
.06
.05
.04
36
40
10
18
4.0
£.tf
*»fi
fid
79
QA
The tables above given, and which have been selected and not
calculated, will serve to explain the inapplicability of the mode of
calculation proposed in various popular works, — namely, for an-
gular thread screws, to divide the diameter by 8 for the pitch,
when, it is said, such screws will all possess the angle of 3 J degrees
nearly ; and for square threads to divide by 4, thus giving an angle
of 7 degrees nearly ; therefore
Angular thread screws of 8 6 4 2 1
would have pitches of 1 i i i i
or rates of 1 1£ 2
which differ greatly from 2£ 3
£ inches diameter
i i1* s'y inches rise
8 16 32 threads per inch,
8 12 20 Whitworth's observa-
tional numbers.
By the use of the constant divisor 8, the one-inch screw agrees
with Whitworth's table, the extremes are respectively too coarse
and too fine ; as instead of 8 being employed, the actual divisors
vary from about 5 to 16, and therefore a theoretical mode would
probably require a logarithmic scheme. But were this followed
out with care, the adjustment of the fractional threads so obtained,
for those of whole numbers, would completely invalidate the pre-
cision of the rule ; and the result would not be in any respect
better than when adjusted experimentally, as at present.
There is little doubt that if we could entirely recommence the
labors of the mechanist, or if we could sweep away all the screw-
ing tools now in use, and also all the existing engines, machines,
tools, instruments, and other works, which have been in part made
through their agency, these proposed scales, or others not greatly
differing from them (as the choice is in great measure arbitrary),
would be found of great general advantage; the former for the
larger, the latter for the smaller works. But until all these myriads
of objects are laid on one side, or that repairs are "no longer wanted
in them, the old tools must from absolute necessity be retained, in
addition to those proposed in these or any other schemes. It
SCREW-CUTTING TOOLS.
485
would be of course highly judicious in new manufacturing estab-
lishments to adopt such conventional scales, as they would, to that
extent, promote this desirable but almost impracticable end, namely,
that of unity of system ; but which, although highly fascinating
and apparently tenable, is surrounded by so many interferences
that it may perhaps be considered both as needless and hopeless to
attempt to carry it out to the fall, or to make the system absolutely
universal ; and some of the circumstances which affect the propo-
sition will be now briefly given.
First, agreement with STANDARD MEASURE, although convenient, is
not indispensable. It may be truly observed, that as regards the
general usefulness of a screw such as Fig. 516, which was sap-
posed to measure } inch diameter, and to have 10 threads per inch,
it is nearly immaterial whether the diameter be three or four hun-
dredths of an inch larger or smaller than f of an inch ; or whether
it have 9, 9T'gth, 9}, 10 J, or 11 threads per inch, or any fractional
number between these ; or whether the thread be a trifle more or
less acute, or that it be slightly truncated or rounded ; so long as
the threads in the screw and nut are but truly helical and alike, in
order that the threads mutually bear upon each other at every part ;
that is, as regards the simple purpose of the binding screw or bolt,
namely, the holding of separate parts in firm contact. And as
the same may be said of every screw, namely, that a small varia-
tion in diameter or pitch is commonly immaterial, it follows
that the good office of a screw does not depend on its having
any assigned relation to the standard measure of this or any other
country.
Secondly, The change of system would cause an inconvenient in-
crease in the number of screwing tools used. Great numbers of excel-
lent and useful screws, of accidental measures, have been made by
various mechanicians ; and the author hopes to be excused for
citing the example with which he is most familiar.
Between the years 1794 and 1800 I. I. Holtzapffel made a
few varieties of taps, dies, hobs, and screw tools, after the modes
explained at pages 457 and 458. These varieties of pitch were
ultimately extended to twelve kinds, of each of which was formed
a deep and shallow hob or screw tool-cutter. These, when meas-
ured many years afterwards, were found nearly to possess in each
inch of their length the threads and decimal parts that are ex-
pressed in the following table :
Approximate Values of I. I. HoltzapffeVs Original Screw Threads.
1
2
3
4
5
g
f
g
9
10
j j
1
10 j
Threads in 1 inch .
6.58
8.25
9.45
13.09
16.5
19.89
22.12
25.71
28.88
36.10
39.83
55.11
The angle of the deep threads is about 50 degrees: of the shallow 60 degrees.
486 THE PRACTICAL METAL-WORKER^ ASSISTANT.
This irregularity of pitch would not have occurred had the screw-
lathc with change-wheels been then in use ; but such was not the
case. For a long series of years 1. 1. Holtzapffel (in conjunction
with his partner, I. G. Deyerlein, from 1804 to 1827) made, as oc-
casion required, a large or small screw, a coarse or fine, a shallow
or deep thread, and so forth. By which accumulative mode, their
series of working taps and dies, together with screw tools, gauges,
chucks, carriers, and a variety of subordinate apparatus, became
extended to not less than one hundred varieties of all kinds.
About one-third of these sizes have been constantly used, up to
the present time, both by H. & Co., and by other persons to whom
copies of these screw tackles have been supplied, and consequently
many thousands of screws of these kinds have been made : this im-
plies the continual necessity for repairs and alterations in old
works, which can only be accomplished by retaining the original
sizes.
Since the period at which H. & Co. made their screw lathe, they
have employed the aliquot threads for all screws above half an inch ;
indeed, most of these have also been cut in the screw lathe. To
have introduced the same method in small binding screws which
are not made in the screw lathe, but with the diestocks and chasing
tools, would have doubled the number of their working-screw tackle,
and the attendant apparatus ; with the risk of confusion from the
increased number, but without commensurate advantage as regards
the purposes to which they are applied.
Doubtless the same reasons have operated in numerous other
factories, as the long existence of good useful tools has often less-
ened, if not annulled, the advantage to be derived from a change
which refers more immediately to engineering works ; and in which
a partial remedy is supplied, as steam-engines, etc., are frequently
accompanied with spare bolts and nuts, and also with corresponding
screw apparatus, to be employed in repairs; the additional cost of
such parts being insignificant, compared with the value of the
machinery itself.
Thirdly: Unless the standard sizes of screws become inconveni-
ently numerous, many useful kinds must be omitted, or treated as
exceptions. For instance, in ordinary binding screws, more particu-
larly in the smaller sizes, two if not three degrees of coarseness
should exist for every diameter, and which might be denominated
the coarse, medium, and fine series ; and again, particular circum-
stances require that threads should be of shallow or of deep angular
sections, or that the threads should be rounded, square, or of some
other kinds ; in this way alone, a fitness for all conditions would
inconveniently augment the number of the standards.
In many cases besides, screws of several diameters are made of
the one pitch. In order, for example, that the hole when worn may
be tapped afresh, and fitted with screws of the same pitch or thread
but a trifle larger ; or that a partially worn screw may be corrected
with the dies or in the lathe, and fitted with a smaller nut of the
SCREW-CUTTING TOOLS. 487
same pitch. A succession of taps of the same pitch also readily
permits a larger screw to be employed, when that of smaller di-
ameter has been found to break, either from an error of judgment
in the first construction of the machine, or from its being accident-
ally submitted to a strain greater than it was intended ever to bear.
It is also in some cases requisite to have right and left-hand
screws of the same pitch, that, amongst other purposes, they may
effect simultaneous yet opposite adjustments in machinery, as in
some universal chucks : and also some few screws, the threads of
which are double, triple, quadruple, and so forth, for giving to
screws of small diameters considerable rapidity of pitch or traverse,
or a fixed ratio to other screws associated with them, in the same
piece of mechanism.
Under ordinary and proper management, the production of a
number of similar pieces may be obtained with sufficient exactitude
by giving to the tool some constant condition. For example, a hun-
dred nuts tapped with the same tap, will be very nearly alike in
their thread ; arid a hundred screws passed through the hole of a
screw-plate, will similarly agree in size, because of the nearly
constant dimensions of the tools, for a moderate period.
In practice, the same relative constancy is given to the dies of
die-stocks and bolt screwing engines, and partly so to the tools of
the screw-cutting lathe. Sometimes the pressure or adjusting screw
has graduations or a micrometer ; and numerous contrivances of
eccentrics, cams, and stops, are employed to effect the purpose of
bringing the die or turning-tool to one constant position, for each
succeeding screw ; these matters are too varied and general to re-
quire more minute notice. Part of such modes may serve sufficiently
well for ten, or even a hundred screws, provided that no accident
occur to the tool ; but if it were attempted to extend this mode to
a thousand, or a hundred thousand pieces, the same tool could not,
even without accident, endure the trial ; it would have become not
only unfit for cutting, but also so far worn away as to leave the
last of the works materially larger than the first.
In respect to screws, the instrument, the size of which claims the
most importance, is perhaps the plug-tap, or that which removes
the last portion of the material, and therefore determines the diam-
eter of the internal thread ; but as the tap is continually, although
slowly, wearing smaller, the first and the last nut made with it un-
avoidably differ a little in size. It is on account of the wearing of
the tap, amongst other circumstances, that when screws and nuts
are made in large numbers, and are required to be capable of being
interchanged, it becomes needful to make a small allowance for
error, or to make the screws a trifle smaller than the nuts.
In order to retain the size of the taps used by Holtzapffel & Co.
they some years ago made a set of original taps exactly of the size
of the proposed screws, and to be called A ; these, when two or
three times used to rub off the burrs, were employed for cutting
regulating dies B, of the form of Fig. 539, with two shoulders, so
488 THE PRACTICAL METAL-WORKER'S ASSISTANT.
that the dies could be absolutely closed, and yet leave n space for
the shaving or cuttings. In making all their plug- taps, they are
first prepared with the ordinary shop tools, until
the taps are so nearly completed, that, grasped Fi •*• ^9-
between the regulating dies B, the latter close
within the fortieth or fiftieth of an inch, therefore
leaving the dies B next to nothing to perform in
the way of cutting, but only the office of regulat-
ing the diameter of the working plug-taps. Should
the dies B meet with any accident, the taps A,
which have to this stage been only used for one
pair of regulating dies, exist for making repeti-
tions of B. This method has been found to fulfil
its intended purpose very effectually for several
years, but at the same time it is not proposed to
apply this or any other system universally.
In conclusion, it may be said that by far the most important
argument in favor of the adoption of screws of aliquot pitches ap-
plies to steam-machinery and similar large works, and that, princi-
pally, because it brings all such screws within the province of the
screw-lathe with change-wheels, which has become, in engineering
establishments and some others, a very general tool. This valua-
ble tool alone renders each engineer in a great measure indepen-
dent of his neighbor, as screws of 2, 2 J, 2 J, 3, 10, or 20 threads in
the inch, are readily measured with the common rule, and copied
with the screw-wheels, and a single-pointed tool, or an ordinary
comb or chasing tool with many points.
And therefore, with the modern facility of work, were engineers
severally to make their screw tackle from only the written measures
of any conventional table, they would be at once abundantly within
reach of the adjustment of the tools, and that without any standard
guages ; the strict introduction of which would almost demand
that all the tools made in uniformity with them should emanate
from one centre, or be submitted to some office for inspection and
sanction — and this would be indeed to buy the occasional advantage
at too dear a rate.
It must, however, be unhesitatingly granted, that the argument
applies but little, if at all, to a variety of screws which from their
smaller feize are not made in the screw lathe, but with die-stocks
and the hand- chasing tools only ; and which are employed in
branches of art that may be considered as almost isolated from one
another, and therefore not to require uniformity.
For instance, the makers of astronomical, mathematical, and
philosophical instruments, of clocks and watches, of guns, of locks
and ironmongery, of lamps and gas apparatus, and a multitude of
other works, possess, in each case, an amount of skill which applies
specifically to these several occupations; so that'"unless the works
made by each are returned to the absolute makers for reparation,
they are at any rate sent to an individual engaged in the same line
of business.
HISTORY OF ELECTRO -METALLURGY. 489
Under these circumstances, it is- obvious that the gun-makers,
watchmakers, and others, would derive little or no advantage from
one system of threads prevailing throughout all their trades ; in
many of which, as before noticed, partial systems respectively
adapted to them already exist. The means employed by the gen-
erality of artisans in matching strange threads, are, in addition,
entirely independent of the screw lathe, and apply equally well to
all threads, whether of aliquot measures or not ; as it is usual to
convert one of the given screws, if it be of steel, into a tap, or
otherwise to file a screw tool to the same pitch by hand, wherewith
to strike the thread of the screw or tap ; and when several screws
are wanted, a pair of dies is expressly made.
But at the same time that, from manifold considerations, it ap-
pears to be quite unnecessary to interfere with so many existing
arrangements and interests, it must be freely admitted that advan-
tage would ultimately accrue from making all new screws of aliquot
measures ; and which, by gradually superseding the old irregular
threads, would tend eventually, although slowly, to introduce a
more defined and systematic arrangement in screw tackle, and also
to improve their general character.
CHAPTER XXIV.
HISTORY OF THE ART OF ELECTRO-METALLURGY.
IN reviewing the rise and progress of any discovery in the arts
and sciences, particularly of one connected with the application of
chemistry to manufacturing purposes, there are two circumstances
which almost invariably demand especial notice. The first is, that
the discovery has been the result of accidental observation — a fact
eliminated .during investigations undertaken for other purposes —
rather than the result of a direct endeavor to make the discovery.
The second is, that, after the discovery has been made known, it is
found that many previously published experiments exhibited re-
sults which bore more or less directly upon the subsequent dis-
covery, and which are consequently sometimes cited to detract from
the merit of the discoverer, and the originality and value of his
discovery. The following historical sketch will show that these
observations directly apply to the discovery of the art of Electro-
Metallurgy :
VOLTA'S DISCOVERY. — At the beginning of the year 1800, Pro-
fessor Volta invented the apparatus which has been named after
him, the Voltaic Pile. As originally constructed by Volta, it con-
sisted of an equal number of round pieces of zinc, silver, and
pasteboard — tlu zinc and silver pieces being each about the size
490
THE PRACTICAL METAL-WORKER'S ASSISTANT.
of a penny, and those of pasteboard a little smaller; the paste
board pieces were soaked in a solution of common salt, and then
with the metals were piled in the following manner: — zinc, silver,
pasteboard ; zinc, silver, pasteboard ; and so on, in the same order,
till all the pieces, amounting to upwards of a hundred, were piled
upon each other, the uppermost plate being of silver, and, as
already stated, the undermost of zinc; these exterior plates, to
each of which a wire is attached, form the terminals or poles of
the pile. Fig. 540 shows the construction of the Pile.
Fig. 540
C— Silver Plate.
Z— Zinc Plate.
W — Pasteboard between.
AA— The Wires in connection with
the Terminal Plates.
By this instrument all the phenomena of an ordinary battery can
be produced.
CHEMICAL DECOMPOSITION'S BY THE PILE. — This discovery
placed in the hands of the philosopher an instrument by which he
could make such investigations as had never previously been con-
ceived to be possible. Nicholson, for example, effected the decom-
position of water and of several metallic salts : and observed, as a
general rule, that in the decomposition of the latter the metal of
the salt was reduced upon the zinc terminal of the pile.
FIRST BATTERY.— Cruikshanks, of Woolwich, with a view to
facilitate the construction of the pile, employed square plates of
copper and zinc, soldered together two and two ; these were
cemented, by means of pitch, into a wooden trough, at the distance
of about a quarter of an inch from each other, and so arranged
that the zinc plates all faced one end of the trough, and the copper
plates the other end. The spaces or cells between every pair of
plates were filled with a solution of common salt, or a mixture of
acid and water, which produced the same effect as the moist cards
in the pile. The trough thus charged with its metals and solution
acted the same part as the Voltaic pile. This was the first of
those instruments now so well known as the "galvanic battery"
DECOMPOSITION JBY THE BATTERY, AND ITS APPLICATION. —
Ouikshanks attached a silver wire to each terminal of his battery,
HISTOKY OF ELECTRO-METALLURGY. 491
and the other ends of these wires he placed in a glass tube. When
this tube was filled with a solution of acetate of lead, and the
electric current was allowed to pass through it for some time, me-
tallic lead was found deposited upon the wire attached to the zinc
terminal of the battery. Solutions of sulphate of copper, nitrate
of silver, and several other salts, were tried with similar results.
The metals, as Cruikshanks expressed it, were " revived" and that
so completely, as to suggest to him the application of the battery
to the analysis of minerals. While Cruikshanks, Nicholson, and
several other gentlemen in this country were making investiga-
tions and applications of voltaic electricity, upon the Continent,
Brugnatelli, Fourcroy, Vauquelin, and Thenard were making
similar investigations, and obtaining similar results.*
DEPOSITION* OF METALS UPON OTHERS. — Brugnatelli, in his
Annals of Chemistry, gives a long list of experiments on the de-
composition of salts by the pile. He observed the transfer of the
elements of a decomposed compound from one pole to another —
that silver, when deposited upon platinum, preserved all its metallic
brightness — and that, when copper or zinc were used in connec-
tion with the silver terminal, or positive pole, of the pile for decom-
posing salts, these metals were dissolved, and deposited upon the
negative pole. The researches of Fourcroy, Vauquelin, and Thenard
gave the same results.
GILDING. — In 1805, Brugnatelli, in a letter to Van Mons, men-
tions, among other scientific facts, that " he had gilt in a complete
manner two large silver medals, by bringing them, by means of a
steel wire, into communication with the negative pole of a voltaic
pile, and keeping them one after the other immersed in ammoniuret
of gold newly made and well saturated."f
EARLY OPINIONS CONCERNING ELECTRO-DECOMPOSITION. — The
above few instances are selected from a host of a similar kind upon
electro-decomposition, to show that the fact of the deposition of
metals by an electric current was familiar to philosophers at this
early stage of the history of galvanism ; that nevertheless, the
phenomenon was never thought of further than as a curious
action of electricity when passing through a solution containing
metals; and that although these effects were produced again and
again, it was only to prove and enforce certain speculative views
respecting the electric fluid. As for example, Brugnatelli had
formed an idea that the electric fluid had some relations- to an acid
which he called the electric acid, and he therefore viewed the decom-
position of solutions, and the obtaining of the metal, which lie
termed an electrate, as the result of the combination of this electric
acid with the metal of the solution. In one of his memoirs upon
this subject, he says — "Gold and platinum are not sensibly altered
by the electric matter which passes through them, though it of ceo
* Wilkinson, Elements of Galvanism, vol. ii. 1804.
\ Phil. Magazine, 1805.
492 THE PRACTICAL METAL-WORKERS ASSISTANT.
happens that the electric current deposits on gold a stratum of zino
oopper, mercury, or silver, according to whichever of these metallic
bodies it traverses."* In the same paper it is several times stated
that gold and platina do not seem sensibly affected by the electric
acid. And, when he communicated the above experiment of gild-
ing the two medals, his object was to show that he had now found
that the electric acid had also the power of acting upon gold ; and
the publication of these results and observations excited no other
idea in the minds of philosophers of that period than that they
were mere scientific curiosities. The editor of the Philosophical
Magazine appended the following note to the extract already
quoted : — " The result here detailed reminds me of one, somewhat
similar, which took place during some experiments performed
some years ago in the Askesian Booms. Some gold leaf was put
loose upon a new piece of copper coin, which was then brought
into the circuit of the pile. A part of the gold was inflamed, and
other portions adhered to the surface of the copper, as completely
as if they had been attached by any common gilding process."f
How THESE RESULTS AFFECT THE DISCOVERY. — We have been
particular in thus noticing the observations of the first pioneers in
electro-chemistry, because these and similar facts of later date
have been brought prominently forward by writers upon electro-
metallurgy, with the apparent intention to detract from the merit
due to the discoverers of the new art ; founding their objection on
the ground that the principle upon which the discovery is founded
is not new. "Electro-metallurgy," says Mr. Smee, "may be said to
have its origin in the discovery of the constant battery by Pro-
fessor Daniell, for in that instrument the copper is continually
reduced upon the negative plate." And again, when speaking of
Daniells' battery, he says — " Mr. M. De la Rue experimented on its
properties, and found the copper plate also covered with a coating
of metallic copper, which is continually being deposited ; and so
perfect is the sheet of copper thus formed, that being stripped off',
it has the counterparts of every scratch of the plate on which it is
deposited.":);
Doubtless these experiments border very closely upon the dis-
covery ; but yet they have no more claim to serve as dates to its
origin than those we have been referring to. But if it be neces-
sary that an originating experiment must have a resemblance to
that which it suggests — such as Daniell's battery ; and the single
cell of electro-metallurgy — why ornit to refer to Dr. Wollaston's
earlier experiments of 1801? He says — "If a piece of silver, in
connection with a more positive metal, be put into a solution of
copper, the silver is coated over with the copper, which coating
will stand the operation of burnishing."§ But in our opinion none
* Brugnatelli, Annals of Chemistry, vol. xviii., and Wilkinson, vol. ii.
t Phil. Mag., 1805.
j Smee, Elements of Electro-M.'tal'urgy, 2d Edition, 1843.
$ Philosophical Transactions, itui.
HISTORY OF ELECTRO -METALLURGY. 493
of these results originated electro-metallurgy: the discovery of that
art, although it is an application of such results as we have described,
was as original on the part of the discoverers, and as unconnected
with these results at the time it was made, as it would have b^i
had the earlier observations never been published. The discovery
seems to have been deduced from results which the discoverers
had obtained in their own experiments, not even while searching
for such a discovery but during investigations instituted for other
purposes.
USE OF OBSERVED FACTS. — It must not be supposed that we
depreciate the value of the published facts upon the decomposition
of salts, nor that we overlook their relation to the discovery which
followed ; for the multiplication of facts, and the improvement of
instruments for experimenting, enlarge our knowledge of the prin-
ciples to be investigated or applied ; they facilitate inquiry, and
increase the number of observers. The circumstances connected
with the discovery of ELECTRO-METALLURGY — of the application
of the decomposing force of an electro current passing through a
solution, will illustrate these observations.
SPENCER'S FIRST EXPERIMENTS. — Mr. Thomas Spencer, of Liver-
pool, states that, in 1837, while experimenting with a modification
of a Daniell's battery, he used a penny piece instead of a plain piece
of copper, as a pole. Copper was deposited from the solution upon
it, and on removing the wire which attached the penny to the zinc
plate he also pulled off a portion of the deposited copper, which he
found to be an exact counterpart or mould of a part of the head and
letters of the coin as smooth arid sharp as the original. But this did
not suggest to him any useful application, until sometime after he
dropped, accidentally, a little varnish upon a slip of copper which he
was about to use in the same way as he had used the pennj piece.
On finding that no deposit of copper took place on the puits where
the varnish had dropped, he then conceived the idea of applying thia
principle to the arts, by coating a piece of copper with varnish 01
wax, and cutting a design through the wax or varnish, leaving the
copper bare, and then depositing upon these parts, so that upon
removing the varnish the design would be left in relief.
JACOBI'S EXPERIMENTS. — While Mr. Spencer was following up
these ideas, the following paragraph appeared in the Athenaewn foi
4th May, 1839 :
"Galvanic Engraving in Relief. — While M.Daguerre and Mr. Fox
Talbot have been dipping their pencils in the solar spectrum, and
astonishing us with their inventions, it appears that Professoi
Jacobi, at St. Petersburgh, has also made a discovery which prom-
ises to be of little less importance to the arts. He has found u
method — if we understand our informant rightly — of converting
any line, however fine, engraved on copper, into a relief, by gal-
vanic process. The Emperor of Eussia has placed at the Pro-
fessor's disposal, funds to enable him to perfect his discovery."
In consequence of this announcement, Mr. Spender, on the 8th
494 THE PRACTICAL METAL-WORiCEtt'3 ASSISTANT.
of May, 1839, gave notice to the Liverpool Polytechnic Institution,
that he should make a communication to them of his process for
effecting results similar to those of Professor Jacobi. But Mi
Spencer appears to have changed his design of reading it to the
aDoVe Institution, in order to have it read at the meeting of the
British Association, which was to take place a short time after.
JORDAN'S EXPERIMENTS. — Meanwhile the announcement of the
Athenaeum was quoted in the London Mechanics1 Magazine for May
llth, 1839, which brought forth a letter from Mr. C. J. Jordan, a
book-printer, dated 22d May, 1839, and published on the 8th June
of the same year in the London Mechanics' Magazine. In this letter
Mr. Jordan describes his experiments upon the same subject, detail-
ing the method of procuring electrotypes, and offering hints for
their application which have since been acted upon with considera-
ble success. The following is a copy of Mr. Jordan's letter, which
was, no doubt, the first published description of the art ip this
country :
"Engraving by Galvanism.
" Sir : — Observing in the last page of a recent Number of your
Magazine, a notice extracted from the Athenseum, relative to a dis-
covery of Professor Jacobi, its perusal occasioned the recollection
of some experiments performed about the commencement of last
summer, with the view of obtaining impressions from engraved
copper plates, by the aid of galvanism, which led me to infer some
analogy in principle with those of the Russian Professor, and may
probably give me the right to claim priority in its discovery and
application. These experiments were abandoned from the want of
that most important element in pursuits of this nature — time; the
writer's share of the said element being occupied in a manner more
imperative than pleasing. I regret, however, not having made it
the subject of an earlier communication, as this would have placed
my pretensions beyond doubt; but, inasmuch as the notice alluded
to is given from memory, and is undescriptive, while I may be
enabled to exhibit the modus operandi, my assertion may be at
least partially substantiated.
" It is well known to experimentalists on the chemical action of
voltaic electricity, that solutions of several metallic salts are decom-
posed by its agency, and the metal procured in a free state. Such
results are very conspicuous with copper salts, which metal may be
obtained from its sulphate (blue vitriol), by simply immersing the
poles of a galvanic battery in its solution, the positive wire becoming
gradually coated with copper. This phenomenon of metallic reduc-
tion is an essential feature in the action of sustaining batteries, the
effect, in this case, taking place on more extensive surfaces. But
the form of voltaic apparatus which exhibits this result in the most
interesting manner, and relates more immediately to the subject of
the present communication, may be thus described: — It consists of
a glass tube, closed at one extremity with a plug of plaster of Paris
FIISTOLY OF ELECTRO- METALLURGY. 495
and nearly filled with, a solution of sulphate of copper ; this tube
and its contents are immersed in a solution of common salt. A plate
of copper is placed in the first solution, and is connected, by means
of a wire and solder, with a zinc plate which dips into the latter.
A slow electric action is thus established through the pores of the
plaster, which it is not necessary to mention here — the result of
which is the precipitation of minutely crystallized copper on the
plate of that metal, in a state of greater or less malleability accord-
ing to the slowness or rapidity with which it is deposited. In
some experiments of this nature, on removing the copper thus
formed, I remarked that the surface in contact with the plate
equalled the latter in smoothness and polish, and mentioned this
fact to some individuals of my acquaintance. It occurred to
me, therefore, that if the surface of the plate was engraved, an
impression might be obtained. This was found to be the case ;
for, on detaching the precipitated metal, the mosvt delicate and
superficial markings, from the fine particles of powder used in
polishing, to the deeper touches of a needle or a graver, exhibited
their correspondent impressions in relief, with great fidelity. It
is, therefore, evident that this principle will admit of improvement,
and that casts and moulds may be obtained from any form of
copper.
" This rendered it probable that impressions may be obtained
from those other metals having an electro-negative relation to the
zinc plate of the battery. With this view, a common printing-
type was substituted for the copper plate, and treated in the same
manner. This also was successful ; the reduced copper coated that
portion of the type immersed in the solution. This, when re-
moved, was found to be a perfect matrix, and might be employed
for the purpose of casting, where time is not an object.
It appears, therefore, that this discovery may be turned to some
practical account. It may be taken advantage of in procuring
casts from various metals, as above alluded to; for instance, a
copper die may be formed from a cast of a coin or medal, in silver,
type metal, or lead, etc., which may be employed in striking im-
pressions in soft metals. Casts may probably be obtained from a
plaster surface surrounding a plate of copper; tubes or any small
vessels may also be made by precipitating the metal abound a wire,
or any kind of surface, to form the interior, which may be removed
mechanically, by the aid of an acid solvent, or by heat.
" C. J. JORDAN."
" To the Editor of the London Mechanics' Magazine"
Clear and perspicuous as this letter is, it did not attract the
hlightest notice. And a few weeks after, we find that its existence
was forgotten even by the editor of the magazine in which it
appeared.
SPENCER'S FIRST PRINTED PAPER UPON ELECTROTYPE. — Mr,
Spencer's communication, referred to above, was, in consequence
496 THE PRACTICAL METAL- WORKER'S ASSISTANT.
of some misunderstanding, not read at the meeting of the, British
Association, but it was immediately afterwards read before the
Polytechnic Institution of Liverpool, at their meeting on the 13th
September, 1839, which was upwards of three months after the
publication of Mr. Jordan's letter in the London Mechanics' Maga-
zine. Mr. Spencer's paper was accompanied with specimens both
of electrotypes and of printing from electrotypes. The publica-
tion of this paper acted like an electric shock upon society, and
men both of science and art became active competitors in this new
field of application ; the one class anxious to bear away the honors
arising from some important improvement ; the other, the profits
which might follow some novel application of the process to their
own or some other branch of manufacture. Indeed, thousands of
all classes and ages, who had never previously given science a
passing thought, became fascinated with the new art, and — the
process being simple and easy to perform — the amateurs soon be-
came excellent electrotypists. With these combined efforts, it
need not be wondered at that in a very short time improvements
of great scientific interest were pointed out, and applications of the
greatest importance to the arts and manufactures of this country
were introduced. In consequence, some of our old and standard
manufactures, as we shall subsequently have occasion to notice at
some length, have already been revolutionized,
HISTORICAL ANOMALY. — During a period of nearly five years
— while the country was passing through an electrotyping mania
— Mr. Spencer held the undivided honor of being the first to
apply the deposition of metals to practical purposes in this coun-
try, but early in 1844, Mr. Henry Dircks, in a letter to the London
Mechanics'9 Magazine, revived Mr. Jordan's letter, and told us that
he was aware of its existence from the time of its first publication.
We cannot eulogise either the policy, or the love of scientific-
truth, which induced Mr. Dircks to remain silent so long, and see
the claims of Mr. Jordan set aside by one whom he considered to
be a mere pretender to the merit of the discovery. Nor, after a
careful and impartial examination of all the details published on
the subject, can we agree to his condemnation of Mr. Spencer's
prior claims ; as he, Mr. Spencer, upon the 8th of May, as already
noticed, stated to a public meeting of the Polytechnic Society of
Liverpool, that he had made a similar discovery previous to any
knowledge of either what Jordan or Jacobi had done, and which
was a publication as much as if printed in the Times or Athen&um,
and especially when followed by a detailed description of the dis-
covery.
It is to be regretted that Mr. Jordan's diffidence, which in this
case was far from being commendable, prevented his setting the
public right upon this important matter. As a consequence, ho
must now be content with a much smaller share of the honor of
the discovery than he might have enjoyed.
OH reviewing the circumstances of this discovery, it strikes us
PIISTORY OF ELECTRO-METALLURGY. 497
as being a- remarkable instance of the unity of intellectual percep-
tion in reference to the general principles of Nature and their ap-
plications ; for we believe that Professor Jacobi, Mr. Spencer, and
Mr. Jordan, viewed the subject of electro depositions in the same
light, and about the same time ; and each, according to their sev-
eral abilities, presented to the public the same discovery, indepen-
dent of the other, excepting the announcement made by one having
hastened the publication of the observations of the others.
The following is Mr. Spencer's original paper on electro-metal-
lurgy, which we give at length, trusting that its importance in con-
nection with the history of the art, and the lucid description of its
practice, will serve as a sufficient apology for not abridging it :
" On Working in Metal by Voltaic Electricity, reprinted from the Pa-
per Published by the Liverpool Polytechnic Society, and read at the
Meeting of September the 12th, 1839, Notice being given May the
8th : Henry Booth, Esq., President, in the Chair.
" In the paper that I have the honor to lay before the society, I
do not profess to have brought forward a perfect invention. My
only object is to point out a means by which, I hope, practical
men may be enabled to apply a great and universal principle of
Nature to the useful and ornamental purposes of life. In this I
may be considered sanguine — an error, I am aware, too often fallen
into by those who, like myself, imagine they have discovered a
useful application of an important principle ; but however this
may fall out, I shall lay an account of its results, with specimens,
successful and unsuccessful, before the members and the public —
previously stating, however, that all my first experiments were
made on a small scale — a method of procedure attended with many
advantages to the experimentalist himself, but having its disadvan-
tage when laid before the public. In this first respect, perhaps,
the chemical experimenter has an advantage over the mechanical
one, as the success of his experiment, when tried on a small scale,
doubly guarantees it if conducted on a still larger scale: with
mechanical results I believe in most instances it is the reverse. But
when the chemist produces his microscopic proofs, the public
are generally slow to believe that such minute appearances should
warrant him in coming to any general conclusion.
"In the latter part of September, 1837, I was induced to make
some electro-chemical experiments, with single pairs of plates,
consisting of small pieces of zinc and equal-sized pieces of copper,
connected together with wires of the latter metal. It was intended
that the action should be slow : the fluids in which the metallic
electrodes were immersed were in consequence separated by thin
discs of plaster, of Paris. In one cell thus formed was placed sul-
phate of copper in solution — in the other, a weak solution of
common salt. I need scarcely add that the copper electrode was
placed in the cupreous solution, the other being in that of the salt.
32
498 THE PRACTICAL METAL-WORKER' S ASSISTANT.
I mention these experiments briefly — not because they are directly
connected with what I shall have to lay before the society, but
because, by a portion of their results, I was induced to come to
the conclusions I have done in the following paper. I was desir-
ous that no action should take place on the wires by which the
electrodes were held together ; and to- attain this object I varnished
them with sealing-wax varnish : but, in one instance, I dropt a
portion on the copper electrode that was attached. I thought
nothing of this circumstance at the moment, but put the experi-
ment in action.
"This operation was conducted in a glass vessel; I had conse-
quently an opportunity of occasionally examining its progress from
the exterior. After the lapse of a few days, metallic crystals had
covered the copper electrode — with the exception of that portion
which had been spotted with the drops of varnish. I at once saw
that I had it in my power to guide the metallic deposition in any
shape or form I chose, by a corresponding application of varnish
or other non-metallic substance.
" I had been aware of what every one who uses a sustaining
galvanic battery with sulphate of copper in solution must know —
that the copper plates acquire a coating of copper from the action
of the battery ; but I had never thought of applying it to a useful
purpose, except to multiply the plates of a species of battery,
which I did in 1836. My present attempt was with a piece of thin
copper plate, having about four inches of superfices, with an equal
sized piece of zinc, connected as before by a piece of copper wire
I gave the copper a coating of soft cement, consisting of beeswax,
resin, and a red earth. It was compounded in the manner recom-
mended by Dr. Faraday, in his work on Chemical Manipulation,
but with a larger proportion of wax. The plate received its coat-
ing while hot. When it was cold, I scratched the initials of my
name rudely on the plate, taking special care that the cement was
quite removed from the scratches, that the copper might be thor-
oughly exposed. This was put in action in a cylindrical glass
vessel, about half filled with a saturated solution of sulphate of
copper. I then took a common gas glass, similar to that used to
envelope an argand burner, and filled one end of it with plaster of
Paris, to the depth of three-quarters of an inch. Into this I put
water, adding a few crystals of sulphate of soda to excite action,
the plaster of Paris acting as a partition to separate the fluids, but,
at the same time, being sufficiently porous to allow the electro-
chemical action to permeate its substance.
" I now bent the wire in such a manner that the zinc end of the
arrangement should be in the saline solution, while the copper
end, when in its place, should be in the cupreous solution. The
gas glass, with the wire, was then placed in the vessel containing
the sulphate of copper.
"It was then suffered to remain at rest, when in a few hours I
perceived that action had commenced, and that the portion of the
HISTORY OF ELECTRO- METALLURGY. 499
copper rendered bare by the scratches had become gradually
coated with pure bright deposited metal, whilst all the surround-
ing portions were not at all acted on. I now saw my former obser-
vations realized; but whether the deposition so formed would
retain its hold on the plate, and whether it would be of sufficient
solidity or strength to bear working if applied to a useful pur-
pose, became questions which I now determined to solve by experi-
ment. It also became a question — should I be successful in these
two points — whether I should be able to produce lines sufficiently
in relief to print from. This latter appeared to depend entirely
on the nature of the cement or etching-ground I might use.
" This I endeavored to solve at once ; and, I may state, it ap-
peared at the time to be the main difficulty, as my impression then
was, that little less than one-eighth of an inch of relief would be
requisite to print from.
" I now procured a piece of copper, and gave it a coating of a
modification of the cement I have already mentioned, and having
covered it to about one-eighth of an inch in thickness, I took a steel
point and endeavored to draw lines in the form of net-work, that
should entirely penetrate the cement, and leave the surface of the
copper exposed. But in this I experienced much difficulty, from
the thickness I deemed it necessary to use ; more especially when
I came to draw the cross lines of the net- work. The cement being
soft, the lines were pushed as it were into each other, and when it
was made of harder texture, the intervening squares of the net-
work chipped off the surface of the metallic plate. However
those that remained perfect I put in action as before.
" In the progress of this experiment I discovered that the solidity
of the metallic deposition depended entirely on the weakness or
intensity of the electro- chemical action, which I knew I had in my
power to regulate at pleasure, by the thickness of the intervening
wall of plaster of Paris, and by the coarseness or fineness of the
material. I made three similar experiments, altering the texture
and thickness of the plaster each time, by which I ascertained that
if the partitions were thin and coarse, the metallic depositions pro-
ceeded with great rapidity, but the crystals were friable and easily
separated; on the other hand, if I made them thicker and of a little
finer material, the action was slower, but the metallic deposition
was as solid and ductile as copper formed by the usual methods
— indeed, when the action was exceedingly slow, I have had a
metallic deposition apparently much harder than common sheet
copper, but more brittle.
" There was one most important and, to me, discouraging circum
stance attending these experiments, which was, that when I heated
the plates to get off the covering of cement, the meshes of copper
net- work occasionally came off with it. I at one time imagined this
difficulty inseparable, as it appeared that I had cleared the cement
entirely from the surface of the copper that I meant to have ex-
posed ; and I concluded that there must be difference in the mole
500 THE PRACTICAL METAL-WORKERS ASSISTANT.
cular arrangement of copper prepared by heat and that prepared
by voltaic action, which prevented their chemical combination.
However, I determined, should this prove so, to turn it to account
in another manner, which I shall relate in the second portion of
the paper.
*' I now occupied myself for a considerable period in making
experiments on this latter section of the subject.
" In one of them I found, on examination, that a portion of the
copper deposition, which I had been forming on the surface of a
coin, adhered so strongly that I was quite unable to get it off —
indeed, a chemical combination had apparently taken place. This
was only on one or two spots on the prominent parts of the coin.
I immediately recollected that, on the day I put the experiment in
action, I had been using nitric acid for another purpose, on the
table I wa? operating on, and that in all probability the coin might
have been laid down where a few drops of the acid had accidentally
fallen. Bearing this in view, I took a piece of copper, coated it
with cement, made a few scratches on its surface until the copper
appeared, and immersed it for a short time in dilute nitric acid,
until I perceived, by an elimination of nitrous gas, that the exposed
portions were acted upon sufficiently to be slightly corroded. I
washed the copper in water, and put it in action as before described.
In forty -eight hours I examined it, and found the lines were en-
tirely filled with copper, I applied heat, and then spirits of turpen-
tine, to get off the cement, and, to my satisfaction, I found that the
voltaic copper had completely combined itself with the sheet ou
which it was deposited.
" I then gave a plate a coating of cement to a considerable thick-
ness, and sent it to an engraver ; but when it was returned I found
the lines were cleared out so as to be wedge-shaped, or somewhat
in the form of a V, leaving a hair line of the copper exposed at
the bottom, and a broad space near the surface ; and where the
turn of the letters took place, the top edges of the lines were
galled and rendered rugged by the action of the graver. This, of
course, was an important objection, which I have since been able to
remedy in some degree by an alteration in the shape of the graver,
which should be made of a shape more resembling a narrow par-
allelogram than those in common use : some engravers have many
of their tools so made. I did not put this plate in action, as I saw
that the lines, when in relief, would have been broad at the top
and narrow at the bottom. I took another plate, gave it a coating
of the wax, and had it written on with a mere point. I deposited
copper on the lines, and afterwards had it printed from.*
•' I now considered part of the difficulties removed : the prin-
cipal one yet remaining was to find a cement or etching-ground,
the texture of which should be capable of being cut to the re-
* This plate was shown to friends, and also specimens of printing from it,
in 1838.
UISTOBY OF ELECTRO-METALLURGY. 501
quired depth, without raising what is technically termed a burr,
and, at the same time, of sufficient toughness to adhere to the
plate, when reduced to a small isolated point, which would neces-
sarily occur in the operation which wood-engravers term cross-
hatching.
" I have since learned, from practical engravers, that much less
relief is necessary to print from than I had deemed indispensable,
and that, on becoming more familiar with the cutting of the wax-
cernent, they would be enabled to engrave in it with great facility
and precision.
" I tried a number of experiments with different combinations
of wax, resins, varnishes, earths, and metallic oxides, all with more
or less success. One combination that exceeded all others in its
texture was principally composed of beeswax, resin, and white
lead. This had nearly every requisite, so that I was enabled to
polish the surface of the plate with it until it was nearly as smooth
as a plate of glass. With this compound I had two plates, five
inches by seven, coated over, and portions of maps cut on the
cement, which I had intended should have been printed off. I ap-
plied the same process to these as to the others, immersing them
into dilute nitric acid before putting them in action ; indeed I suf-
fered them to remain about ten minutes in the solution. I then put
them into the voltaic arrangement. The action proceeded slowly
and perfectly for a few days, when I removed them. I applied
heat as usual, to remove the cement, but all came away, as in a
former instance — the voltaic copper peeling off the plate with the
greatest facility. I was much puzzled at this unexpected result ;
but, on cleaning the plate, I discovered a delicate trace of lead, ex
actly corresponding to the lines drawn on the cement previous to
the immersion in the dilute acid. The cause of this failure was
at once obvious : the carbonate of lead I had used to compound
the etching-ground had been decomposed by the dilute nitric acid
and the metallic lead thus reduced had deposited itself on the ex
posed portions of the copper plates, preventing the voltaic copper
from chemically combining with the sheet copper,. I was now
with regret obliged to give up this compound, and to adopt another,
consisting of beeswax, common resin, and a small portion of
plaster of Paris. This seems to answer the purpose tolerably,
though I have no doubt, by an extended practice, a better may
still be obtained by a person practically acquainted with the etch-
ing-grounds in use among engravers.
" I now proceed to the second, and I believe the most satisfac-
tory portion of the subject. Although I have placed these experi-
ments last, some of them were made at the same time with the
others already described, and some of them before ; but, to render
the subject more intelligible, I have placed them thus.
" The ^members of the society will recollect that, on the first
evening it met, I read a paper on the ' production of metallic veins
in the crust of the earth,' and that among other specimens of cupre-
502 THE PRACTICAL METALWORKER'S ASSIST^ i.
ous crystallization which I produced on that occasion, I exhibited
three coins — one wholly covered with metallic crystals, the other
on one side only. It was used under the following circumstances
AY hen about to make the experiment, I had not a slip of copper
at hand to form the negative end of my arrangement, and, as a
good substitute, I took a penny and fastened it to one end of the
wire, and put it, in connection with a piece of zinc, in the apparatus
already described.
" Voltaic action took place, and the copper coin became covered
wjth a deposition of copper in a crystalline form. But, when
about to make another experiment, and being desirous of using
the piece of wire used in the first instance, I pulled it off the coin
to which it was attached. In doing this, a piece of the deposited
copper came off with it ; on examining the under portion of which,
I found it contained an exact mould of a part of the head and
letters of the coin, as smooth and sharp in every respect as the
original on which it was deposited. I was much struck with this
at the time ; but, on examination, the deposition metal was very
brittle. This, and the fact that it would require a metallic nucleus
to aggregate on, made me apprehensive that its future usefulness
would be materially abridged ; but it was reserved for future ex-
periment, and in consequence laid aside for a time, until my atten-
tion was recalled to the subject in a subsequent experiment, already
detailed, by the drops of varnish on a slip of copper. Finding in
that instance that the deposit would take the direction of any non-
conducting material, and be, as it were, guided by it, I was induced
to give the previous branch of the subject a second trial, because
I had, in the first instance, supposed that the deposition would
only take place continuously, and not on isolated specks of a
metallic surface, as I now found it would ; but the principal in-
ducement to investigate the subject was the fact of finding that
deposited copper had much more tenacity than I at first imagined.
" Being aware of the apparent natural law which limits metallic
deposition by voltaic electricity, excepting in the presence of a
metallic body, I perceived that the uses of the process would, in
consequence, be extremely limited, except in the multiplication of
already engraved plates, as, whatever ornament it might produce,
it would only be done by adhering to the condition of a metallic
mould.
" I accordingly determined to make an experiment on a very
prominent copper medal. It was placed in a voltaic circui
already described, and deposited a surface of copper on one of its
sides to about the thickness of a shilling. I then proceeded to get
the deposition off. In this I experienced some difficulty, but ulti-
mately succeeded. On examination with a lens, every line was as
perfect as the coin from which it was taken. , I was then induced
to use the same piece again, and let it remain 'a much longer tinia
in action, that I might have a thicker and more substantial mould,
m order to test fairly the strength of the metal. It was accord-
HISTORY OF ELECTRO- METALLURGY. 503
ingly pat again in action, and let remain until it had acquired a
much thicker coating of the metallic deposition ; but on attempt-
ing to remove it from the medal I found I was unable. It had,
apparently, completely adhered to it.
"I bad' often practised, with some degree of success, a method
of preventing the oxidation of polished steel, by slightly heating
it until it would melt fine beeswax : it was then wiped, apparently
completely on; but the pores or surface of the metal became im-
pregnated with the wax.
'•' I thought of this method, and applied it to a copper coin.
" I first heated it, applied wax, and then wiped it so completely
oft' that the sharpness of the coin was not at all interfered with. I
proceeded as before, and deposited a thick coating of copper on
its surface. Being desirous to take it off, I applied the heat of a
spirit-lamp to the back, when a sharp crackling noise took place,
and I had the satisfaction of perceiving that the coin was com-
pletely loosened. In short, I had a most complete and perfect
copper mould of one side of a half-penny.
"I have since taken some impressions from the mould thus
taken, and, by adopting the above method with the wax, they are
separated with the greatest e;-
•• Bv this experiment it would appear that the wax impregnates
the surface of the metal to an inconsiderable depth, and prevents
a chemical adhesion from taking place on the two surfaces ; and I
can only account for the crackling noise, on separation, by suppos-
ing it probable that the molecular arrangement of the voltaic
metal is different from that subjected to percussion, and this differ-
ence causes an unequal degree of expansibility on the application
of heat.
" I became now of opinion, that this latter method might be
applied to engraving much better than the method described in
the first portion of this paper. Having found in a former experi-
ment that copper in a voltaic circuit deposited itself on lead with
as much rapidity as on copper, I took a silver coin, and put ic be-
tween two pieces of clean sheet-lead, and placed them under a
common screw-press. From the softness of the lead, I had a com-
plete and sharp mould of both sides of the coin, without sustain-
ing injury. I then took a piece of copper wire, soldered the lead
to one end, and the piece of zinc to the other, and put them into
the voltaic arrangement I have already described. I did not, in
this instance, wax the mould, as I felt assured that the deposited
copper would easily separate from the lead by the application of
heat, from the different expansibility of the two metals.
" In this result I was not disappointed. When the heat of a
spirit-lamp was applied for a few seconds to the lead, the copper
impression came easily oi£ So complete* do I think this latter
portion of the subject, that I have no hesitation in asserting that
fae-similfes of any coin or medal, no matter of what size, may
be readily taken, and as sharp as the original. To test further tho
504 THE PRACTICAL METAL-WORKER'S ASSISTANT.
capabilities of this method, I took a piece of lead plate, and stamped
some letters of its surface to a depth sufficient to print from, when
in relief. I deposited the copper on it, and found it came easily
off, the letters being in relief.
" Finding from this experiment that the extreme softness of lead
allowed it to be impressed on by type metal, I caused a small por-
tion of ornamental letter-press to be set up in type, and placing it
on a planed piece of sheet lead, it was subjected to the action of a
screw press.
"After considerable pressure, it was found that a perfectly sharp
mould of the whole had been obtained in the lead. A wire was
now soldered to it, and it was placed in an apparatus similar in
principle, but larger than the one already described. At the end
of eight days from this time, copper was deposited to one-eighth of
an inch in thickness ; it was then removed from the apparatus, and
the rough edges of the deposited copper being filed offj it was sub-
jected to heat, when the two metals began to loosen. The separa-
tion was completed by inserting a piece of wedge-shaped wood
between them.
" I had now the satisfaction of perceiving that I had by these
means obtained a most perfect specimen of stereotyping in copper,
which had only to be mounted on a wooden block to be ready to
print from.
" From the successful issue of this experiment, which was mainly
due to the susceptibility of the lead, I was induced to attempt to
copy a wood engraving by a similar method, provided the wood
would bear the requisite pressure. Knowing that wood engrav-
ings are executed on the end of the block, I had better hopes of
succeeding, the wood being less likely to sustain injury.
" I accordingly procured a small wood block, and placed its en-
graved surface in contact with a piece of sheet lead made very clean,
and subjected it to pressure, as in the former instance. I had now,
as before, the gratification of perceiving that a perfect mould of the
little block had been obtained, and no injury done to the original.
Several wood engravings and copperplates were subjected to similar
treatment, and are now in process of being deposited on in the
apparatus before me.
"I now come to the third and concluding portion of the experi-
ments on this subject. The object being to deposit a metallic sur-
face on a model of clay, wood, or other non- metal lie body — as,
otherwise, I imagined the application of this principle would be
extremely limited. Many experiments were made to attain this
result, which I shall not detail, but content myself with describing
those which were ultimately most successful.
" I procured two models of an ornament, one made of clay, and
the other of plaster of Paris, soaked them for some time in linseed-
oil, took them out, and suffered them to dry — fi'fst getting the oil
clean off the surface. When dry, I gave them a thin coat of mastic
varnish. When the varnish was nearly dry, but not thoroughly so, I
HISTORY OF ELECTRO-METALLURGY. 505
sprinkled soma bronze powder on that portion I wished to make a
mould of. This powder is principally composed of mercury and
sulphur, or it may be chemically termed a sulphuret of mercury.
There is a sort that acts much better, in which is a portion of gold.
I had, however, a complete metalliferous coating on the surface
of the model, by which I was en^bl^d to deposit a surface of cop-
per on it, by the voltaic method I have already described. I have
also gilt the surface of a clay model with gold leaf, and have been
successful in depositing copper on its surface. There is likewise
another, and as I trust it will prove, a simpler method of attaining
this object ; but as I have not yet sufficiently tested it by experiment,
I shall take another opportunity of describing it."
[At the close of the paper, several specimens of coins, medals, and
copper plates, some of them in the act of formation by the voltaic
process, were exhibited by Mr. Spencer to the Society.]
PLUMBAGO AS A COATING. — Shortly after Mr. Spencer's paper
was published, several important improvements were introduced,
one or two of which we will refer to here, and will give the others
when detailing the processes to which the improvements were ap-
plied. The first was the use of plumbago or black lead, to give
the surface of non-metallic bodies a conducting property. This
was the discovery of Mr. Robert Murray, a gentleman of high at-
tainments and unassuming manners, who communicated the process
to the members of the Royal Institution orally. The Society of
Arts afterwards awarded to Mr. Murray a silver medal, as an ex-
pression of their sense of the value of the discovery. Seldom was
reward more deserving, or a discovery more important to the pur-
poses to which it was to be applied, for this application at once
freed electro-metallurgy from every bond : it was no longer necess-
ary to use either metallic moulds, or moulds having metal reduced
upon their surfaces by chemical means — which, according to the
processes then known, was both tedious and uncertain, and only
applicable to certain substances. Plumbago possessed all the re-
quisite properties : it was convenient, plentiful, and cheap, easily
applied, and equally effective for every substance on which the
electrotypist desired to obtain a deposit, or which he could wish to
cover with metal, either for useful or ornamental purposes.
SEPARATE BATTERY. — The second improvement to be noticed is
one that must have followed the original discovery very soon, namely,
the application of a separate battery for the purposes of deposition.
This was suggested by Mr. Mason. Although those instances of
deposition of metals which have been referred to in the early history
of galvanism were effected by means of separate batteries, namely,
by placing the ends of the wires attached to the terminals of the
battery in the solution to be decomposed, still the discovery under
THE PRACTICAL METAL-WORKERS ASSISTANT.
Fig. 541.
consideration was made by means of what is termed the single cell.
It consisted in simply attaching by a wire the article upon which
a deposition was to be made to a piece of zinc, and immersing the
zinc in diluted acid, and the other article in a solution of the metal
to be deposited ; the two liquids being separated by a porous par-
tition, or diaphragm, such as moist bladder, or unglazed porcelain.
In this case, the whole electricity was expended within the cell, to
deposit the metal within or upon the mould. By Mr. Mason's dis-
covery, the electricity generated in the cell could be made to do an
equivalent of work in a separate cell as well — making the original
arrangement the generating cell or battery to the second cell. In
this last cell was also a solution of a metal having in it a sheet of
similar metal attached to the copper of the first cell, and the mould
to be covered was attached to the zinc of the first cell. Fig. 541
is an illustration of Mason's improvement, which consisted in caus-
ing a medal, in the act of being deposited, to serve as part of a
battery for the deposition of another medal.
o2, Outer vessel filled with sulphate of copper ; o1, another ves-
sel, with p, a porous cell filled with dilute acid, in which is placed
z a zinc plate, which is connected by a wire with a *nedal mf in
• the second vessel charged with sul-
phate of copper. The medal, m, in
the first cell, is connected by a wire
to a piece of copper, c, in the second
cell : the electricity passes from the
zinc z to m, and by the wire to c,
then to m't and by the wire back to
the zinc z.
The use of a separate battery, how-
ever self-evident, was a valuable ad-
dition to the electro-metallurgist for
many of his operations ; although
for some purposes the original single
cell is to be preferred.
LAWS OF DEPOSITION. — As might have been expected in the
excitement occasioned by the announcement of a new art, every
individual experimenter became so engrossed by his own investi-
gations and their results, as to overlook the labors of others, and
at last to lay claim to the honor of originating all the discoveries
they announced; while the truth is, that nearly all the important
facts of electro -metallurgy appear to have occurred almost simul-
taneously to various experimenters. We shall quote one or two
instances of these absorbing claims, as it is important to rectify the
errors they contain, because no successful laborer, however humble,
in the field of science or art, should be overlooked by his fellow-
laborer whose opportunities for research may be much more favor
able.
HISTORY OF ELECTRO-METALLURGY.
507
Extract from Smee's "Electro- Metallurgy''
"The laws regulating the reduction of all metals in different
states were first given in this work as the result of my own dis-
coveries. By these we can throw down gold, silver, platinum, pal-
ladium, copper, iron, and almost all other metals, in three states,
namely, as a black powder, as a crystalline deposit, or as a flexible
plate. These laws appear to me at once to raise the isolated facts
known as the electrotype into a science, and to add electro- metal-
lurgy as an auxiliary to the noble arts of this country."
That Mr. Smee discovered the laws referred to we have not the
slightest doubt: they were published as laws in his book, and they
are commonly quoted as Mr. Smee's ; nevertheless, he was not the
first who discovered them ; the same laws were pointed out by
Mr. Spencer, in his original paper just quoted, published eighteen
months previously to the appearance of Mr. Smee's work, as will
be seen from the following extracts :
Laws given by Smee.
"Law I. — The metals are in-
vaViably thrown down as a black
powder, when the current of
electricity is so strong, in rela-
tion to the strength of the solu-
tion, that hydrogen is evolved
from the negative plate of the
decomposition cell.
"Law II. — Every metal is
thrown down in a crystalline
state, when there is no evolution
of gas from the negative plate,
or no tendency thereto.
"Law III. — Metals are re-
duced in the reguline state, when
the quantity of electricity, in
relation to the strength of the
solution, is insufficient to cause
the production of hydrogen in
the negative plate of the decom-
position trough, and yet the quan-
tity of electricity very nearly
suffices to induce that phenom-
enon."
Laws given ly Spencer.
"I discovered that the solidity
of the metallic deposition de-
pended entirely on the weakness
or intensity of the electro-chem-
ical action, which I knew I had
in
my power to regulate at
pleasure, by the thickness of the
intervening wall of plaster of
Paris, and by the coarseness or
fineness of the material. I made
three similar experiments, alter-
ing the texture and thickness
each time, by which I ascer-
tained, that if the partitions were
thin and coarse, the metallic de-
position proceeded with great
rapidity, but the crystals were
friable and easily separated ; on
the other hand, if I made them
thicker, and of a little finer ma-
terial, the action was slower, but
the metallic deposition was as
solid and ductile as copper formed
by the usual methods. Indeed,
when the action was exceedingly
slow, I have had a metallic depo
sition much harder than common
sheet copper, but more brittle."
The identity of these deductions or laws requires no comment ,
and, comparing the circumstances of the one having nothing but
508 THE PRACTICAL METAL-WORKERS ASSISTANT.
the rude apparatus of a new-born art suggested by himself, to that
of the other, enjoying the advantage of eighteen months improve-
ments, Mr. Spencer is astonishingly correct, and his name should
be identified with the discovery of these laws. The claim of origi-
nality involved in the inference drawn by Mr. Smee, though for-
midable at first sight, is nevertheless, without foundation. Mr.
Smee says : " These laws appear to me at once to raise the isolated
facts known as the electrotype into a science, and to add electro-
metallurgy as an auxiliary to the noble arts of this country" Unfor-
tunately for the validity of Mr. Smee's claim, patents were taken
out long previous, both in England and France, for the applica-
tion of the electro-depositions to the arts. And Messrs. Elkington's
patent for silvering and gilding by this process — a patent which
has not yet been superseded — was not only published in full detail,
but was in extensive operation months before the publication of
Mr. Smee's book. Nevertheless, the publication of Mr. Smee's
book did good service to the art of electrotyping ; and the inven-
tion of his battery has so identified his name with the science, that
it will go down to posterity as that of an active and successful
laborer in the field of electricity : to Mr. Smee we owe, moreover,
the very appropriate name for the art, Electro-metallurgy.
WORKS PUBLISHED ON ELECTRO-METALLURGY. — Besides many
interesting papers in journals and magazines, several separate works
were published on this art. Some months previously to the publi-
cation of Mr. Smee's work, Mr. Spencer had given the world "In-
structions for the multiplication of works of art in metal by voltaic
electricity;" and shortly after Mr. Smee's work appeared, we had, in
rapid succession, Walker's Electrotype Manipulation, Sturgeon's Art
of Electrotyping, Shaw's Manual of Electro-metallurgy, etc., all show-
ing much practical knowledge of the subject. Walker's Manipu
lation, from its practical nature and its concise form, became the
favorite of the amateur, and did more to popularize the art than all
the others put together ; and although little pretensions were made
to originality, the author will not fail to have an honorable remem-
brance in the history of the art.
PATENTS TAKEN OUT FOR ELECTRO-METALLURGY. — The applica-
tion of the art to useful purposes was so self-evident and so eagerly
sought after, that no less than ten patents were taken out for useful
applications, between the discovery of the art and the close of 1841 ;
and not a year has passed since, without adding patents for certain
improvements, and applications of Electro- metallurgy to some par-
ticular branch of manufacture, several of which will be noticed in
their proper places, as many of them, although based upon right
principles, were commercially speaking, entire failures.
DESCRIPTION OF GALVANIC BATTERIES. 509
CHAPTER XXV.
DESCRIPTION OF GALVANIC BATTERIES, AND THEIR RESPECTIVE
PECULIARITIES.
NOMENCLATURE. — The terms that are employed to denote the
various parts of a galvanic battery, and of other electrotype arrange-
ments, frequently puzzle the student, and lead him into difficulties.
Before we proceed to describe the various forms of the battery, we
shall, for this reason, give a preliminary account of the nomencla
ture of galvanism.
The two extremities of a battery have long been called Poles —
one of them the Positive, and the other the Negative, Pole. But
objections have been taken to the use of the terms negative, positive,
and pole, on the ground that such terms do not convey a correct
idea of the circumstances or of the effects produced. Before con-
necting the two metals or extremities of a battery, there is no elec-
tricity evolved, nor is there any electrical tension on any part of
the arrangement; and when the connection is formed the electricity
simply makes a circuit, it is therefore supposed that no particular
portion of that circuit can be said to be either negative or positive
to another portion.
PROPOSED TERMS. — Various terms have been suggested as sub-
stitutes for negative and positive, and also for pole. Dr. Faraday
has proposed the following : for pole, he substitutes electrode, which
signifies a way; for the negative pole, cathode, signifying downwards;
and for the positive pole, anode or upwards. To understand these
terms properly, we must suppose a battery lying upon the ground
with its copper (positive) end to the east, and the wire connecting
the ends of the battery bent into an arch similar to the course of
the sun; the electric current will thus flow up from the east end of
the battery, and descend into it at the west end. The fluid that is
decomposed by a current of electricity passing through it is termed
by Faraday an electrolyte; the elements liberated by this decomposi-
tion he terms ions, distinguishing those liberated at the cathode as
cations, which in sulphate of copper would be the metal, and those
liberated at the anode as onions, which would be the acid portion
of the sulphate of copper.
The late Professor Daniell, disapproving of the terms cathode
and anode, substitued platinode for the negative, and zincode for the
positive, pole. We think these terms are better adapted for electro-
metallurgy than cathode and anode, which have no direct refer-
ence to ordinary conditions; while zincode distinctily expresses
the substance dissolved, and platinode the element not acted upon.
Professor Graham adopts the terms zincous and chlorous poles, as
synonymous with zincode and platinode, or positive and negative.
Although the terms positive, negative, and pole, rnay not be the
510 THE PRACTICAL METAL-WORKERS ASSISTANT.
best, still, under all the conditions of electro-metallurgy, we deem
them as appropriate as any of the proposed substitutes, some of
which are based on supposed conditions which have not been
proved, and may be found incorrect.
When we shall have occasion to use the two terms pole and elec-
trode, these will be used synonymously: positive and negative elec-
trode are synonymous with positive and negative pole.
Electrolyte will be applied to a solution when undergoing decom-
position by the electric current passing through it.
The positive electrode, or pole, is that metal in the electrolyte
which is being dissolved, or, if not capable of being dissolved,' at
which the acid or solvent of the electrolyte is being liberated, as
when sulphate of copper forms the electrolyte, the sulphuric acid
is liberated. The negative electrode, or pole, is that metal or sub-
stance in the electrolyte upon which the metal is being deposited
by the influence of the electric current, such as a rnedal upon which
copper is being deposited in an electrotype process.
BATTERIES.
SINGLE PAIR OF PLATES.— If a piece of ordinary metallic zinc
be put into dilute sulphuric acid, it is speedily acted upon by the
acid, and hydrogen gas is at the same time evolved from its sur-
face, having a disagreable smell arising from impurities contained
in the zinc or acid. If the zinc be taken out, and a little mercury
be rubbed over its surface, an amalgamation takes place between
the two metals: the plate becomes of a beautiful bright silver
appearance. If the zinc thus amalgamated be again put into the
dilute acid, there is no action, for the mercury retains the zinc with
sufficient force to protect it from the acid. If a piece of copper be
immersed along with the zinc, and the two metals be made to touch
each other, a particular influence is induced among the three ele-
ments, zinc, copper, and acid ; the acid again acts upon the zinc as
if no mercury was upon it, but the hydrogen is now seen to escape
from the surface of the copper ; this action will go on as long as
the two metals are kept in contact. Or if, instead of causing the
two metals to touch, a wire be attached to each, and their opposite
ends are placed in a little dilute acid in another vessel, the same
action will take place between the zinc and copper as when they
were in contact ; but in this instance, the ends of the two wires
which dip into the vessel containing acid will undergo a change :
the one attached to the zinc will give oft' a quantity of hydrogen
gas, while the one attached to the copper, supposing it to be also
copper, will rapidly dissolve.
Figure 542. Represents the zinc and copper, placed in dilute
sulphuric acid, brought into contact; in this experiment, gas will
be seen escaping from the copper.
Figure 543. Zinc and copper, placed in dilute acid, and wires
attached, which, when connected, will exhibit the same effects as
in the first case.
DESCRIPTION OF GALVANIC BATTERIES
511
Figure 544. Shows the wires connected by means of a liquid,
such as acid and water, sulphate of copper, etc.
Figs. 542
543
544.
y
The copper and zinc, c and z, with the acid in the first vessel,
Figure 544, constitute a battery of one pair. The wine glass e, wi
acid, in which the wires are placed, is termed the decomposition
cell.
BEST KIND OF ZINC. — The zinc used for the battery should be
milled or rolled zinc, not thinner than Jth of an inch, otherwise the
waste will be very great ; for amalgamated zinc, when it becomes
thin, is so tender and brittle, that the utmost care cannot preserve
it whole. The best thickness for the zincs, when their size is
upwards of four inches square, is Jth of an inch ; but if under
this size, Jth to T3gth of an inch is the proper thickness. Cast
plates of zinc should not be used, as they are negative to rolled
zinc, and give less electrical power : they are so porous that no
amalgamation will protect them from the action of the acid — pro-
ducing " local action," as it is termed, which is not only a waste of
zinc and acid, but prevents, to a great extent, the production of the
quantity of electrical force which the surface of the zinc in use is
calculated to give.
AMALGAMATION OF THE ZINC PLATES. — The amalgamation of
zinc is a process exceedingly simple ; nevertheless, if care be not
taken, a very great loss in mercury and zinc is soon effected.
A stoneware pan is best to use, and should be sufficiently capa-
cious to allow the zinc plate to lie flat within it : a mixture of
eight parts water, and one part sulphuric acid, should be put into
the pan. sufficient in quantity to cover the zinc plate, which should
lie in it till the surface is perfectly bright. The pan is now raised
on the one side, and a little mercury put into the lower part, care
being taken that the zinc does not touch the mercury, to prevent
which is the object of raising the pan on one side. A little coarse
tow, tied to the end of a piece of wood, is dipped into the mercury,
which lifts small portions of the metal mechanically, which is then
rubbed with considerable pressure upon both sides of the zinc
plate, over which the mercury flows easily : the plate is then
washed, by dipping it into clean water, and is next made to stand
upon its edge in another pan, with two small pieces of wood under
512 THE PRACTICAL METAL- WORKER'S ASSISTANT.
•
it, so as to allow the mercury to drain from it. Instead of tow, an
old scratch brush is generally used in plating factories : this is a
brush made of fine brass wire, tied upon a piece of wood ; but we
prefer tow, when carefully employed, as the brass wire amalga-
mates with the mercury, and causes a loss of that metal. After
the zincs have drained for a few hours, the process should be
repeated, only it is not necessary to allow the metal to lie in the
acid in the second process previous to rubbing in the mercury :
after draining a few hours the second time, amalgamation is com-
pleted. In the first process a plate, of a foot square, amalgamated
on both sides, will retain three ounces of mercury; but for the
second process, or any time after, the same size of plate will only
retain 1 J ounces of mercury.
Zinc rapidly absorbs mercury, which permeates the whole metal.
If the mercury was in quantity, the zinc would dissolve in it ;
hence the propriety of rubbing the mercury into the zinc, only in
small portion, for if allowed to imbibe as much as it is capable of
doing, it would not only be a loss of mercury, but the plate would
become exceedingly brittle. When too much mercury is used, a
portion cf it will filter out from the plate by standing, but it carries
with it some zinc dissolved, which tends to deteriorate the quality
of the metal for the battery.
The zinc in the battery, after being used, should never be allowed
to lie in the acid when the battery is not in use, but should be taken
out, and the surface carefully brushed with a hard hair brush, in
water, and then laid by in a safe place. The matter thus brushed
oft; being an amalgam of zinc, is to be carefully collected, arid kept
in dilute sulphuric acid, or in the waste acid from the batteries .
most of the zinc in this amalgam will dissolve out, so that a great
portion of the mercury may be recovered, or by placing these
brushings in a coarse cloth bag, arid subjecting it to pressure in a
screw-press, most of the mercury may by this means be recovered.
ECONOMY IN AMALGAMATION. — If the battery is to be used sel-
dom, and only for a short period at a time, another method of
amalgamation may be adopted. The zinc plate, after lying in the
dilute acid till the surface is bright, may be rubbed over with a
solution of nitrate of mercury, which gives a very thin amalgama-
tion ; but this method is unsuitable if the battery is to be in use
for several hours together.
When a battery is being worked daily, it will be advisable to
repeat the amalgamation from time to time, otherwise local action
will begin, and the working power of the battery be weakened,
while the loss in zinc will be increased.
The following is the proportional rate which we have found on
the large scale under the most favorable circumstances. A new
y-inc plate, amalgamated as described, working continuously —
24 hours, zinc lost 12 J ounces — copper deposited 12 ounces;
48 hours, zinc lost 20 J ounces — copper deposited 17 ounces*
60 hours, zinc lost 34 ounces — copper deposited 24J ounces.
DESCRIPTION OF GALVANIC BATTERIES. 518
From these and similar data we found that the most economical
way of using zincs is the following : after being in the battery
twenty-four hours, they are to be taken out, brushed, and laid
aside ; after working other twenty-four hours, they are to be again
brushed and immediately re-amalgamated : if these directions are
attended to, J ounce of mercury will be sufficient for one foot
square of zinc, both sides.
The advantages of proper amalgamation will be made more evi
dent in the sequel. We have only to add here, in consequence of
an oft-expressed fear of the danger of working with quicksilver,
that no apprehension need be felt : the skin does not absorb it, and
there being no heat required in the operation that could convert
the mercury into vapor, the only state in which it is dangerous, no
salivation can take place.
DISTANCE BETWEEN THE BATTERY PLATES. — To return again
to the battery -cell. It will be found that if the two metals — the
zinc and copper in acid, Fig. 544 — be put very close to each other,
the action will be much more rapid than when they are far apart.
It will also be found that, allowing the zinc and copper to be kept
at one distance, but the wires in the decomposition-cell to be put at
different distances, similar results will take place. When the wirea
are close the action in the battery-cell will be more powerful than
when the two wires are put farther apart : these properties are ap
plicable to all batteries and decomposition-cells of every kind.
The following results will give an idea of the relations of these
several conditions :
1st. One pair of copper and zinc plates, measuring superficially
6 square inches, were immersed in a solution consisting of 1 acid
to 35 water : plates of copper of equal size to those of zinc and
copper were laid in the decomposition-cell, which was then filled
with a liquid of equal strength to that in the battery-cell ; the
plates in the battery-cell and the decomposition-cell were then
placed one inch apart : in four hours
The zinc in the battery-cell lost by dissolving 10J grains ;
The copper dissolved in decomposition-cell 10 grains.
2d. The battery-plates were put 12 inches apart, and the plates
in decomposition-cell 1 inch apart : in four hours
There were dissolved in the battery-cell, zinc 7 grains ;
In decomposition-cell, copper 6 grains.
3d. The battery plates were placed 1 inch apait, and the plates
in decomposition-cell 12 inches apart : in four hours
The zinc in battery-cell lost 4J grains ;
The copper in decomposition-cell lost 3J grains.
These results show the importance of attending to the condi
tions of the respective r gents, and also, that distance in the decom
position-cell offers greater resistance than distance in the battery
cell.
DIFFERENT ELEMENTS OF BATTERIES. — Although our observa
lions have been made on zinc, copper, and dilute sulphuric acid in
33
514 THE PRACTICAL METAL-WORKER'S ASSISTANT.
the battery-cell, still these are not the only essential elements in a
battery, as almost any two metals with a liquid similarly arranged
will produce an electric current ; but the current will vary accord-
ing to the nature of the metals employed, and the effects produced
upon them by the solution in which they are placed. If the ex-
citing solution has the power of acting upon both metals, as when
zinc and copper are immersed in dilute nitric acid, the current of
electricity produced by the action of the acid upon the zinc will
be neutralized to an extent corresponding to the relative action of
the acid upon the copper. To have any effective electrical power,
it is necessary that one of the metals employed be capable of com-
bining easily with one of the elements of the solution in which
they are placed, and forming a soluble salt, while the other does
not ; and the power obtained under proper circumstances has an
intimate relation with these two properties in contrast. The metal
which undergoes solution is termed the positive rnetal, the other
the negative metal. Metals are not considered to possess any in-
trinsic negative or positive principle ; their relations in this respect
are governed solely by the circumstances in which they may be
placed. For instance, if we connect a piece of copper and a piece
of iron, and immerse them in acidulated water, the iron is dissolved,
and is positive in relation to the copper ; but if the same metals
are immersed in a solution of yellow hydro-sulphuret of potassium,
the copper is dissolved, and is positive relatively to the iron.
Hence, to obtain a galvanic battery, the conditions are simply to
provide two metals, and immerse them in a solution capable of
acting upon the one and not upon the other. The first table shows
the order in which the common metals stand to each other, in re-
spect of their relative negative and positive properties, when im-
mersed in water acidulated with sulphuric acid. The second table
is given by Gmelin as the relations of the metals, in water and sea
water, the most intensely negative metal standing highest, and the
metal which acts most positively standing lowest :
Platinum Platinum
Gold Gold
Antimony Silver
Silver , Copper
Nickle Bismuth
Bismuth Antimony
Copper Iron
Lead Tin
Iron Lead
Tin Cadmium
Cadmium Zinc
Zinc
According to this arrangement, each metal is positive with
aspect to all that stand before it, and the electrical conditions of
DESCRIPTION OF GALVANIC BATTERIES. 515
any mir become the more contrasted the further apart they stand
in the scale. Thus, a battery composed of zinc and platinum is
much more powerful than one composed of zinc and copper; and
again, copper and iron make a very weak battery.
A battery may also be formed by having one metal and two
kinds of solutions, separated by a porous diaphragm. For example,
we may have strong nitric acid in one division, and dilute sulphuric
or muriatic acid in the other ; and by putting into each a piece of
clean iron, a powerful current is obtained. These and several
other arrangements of solutions and metals, are expensive and
troublesome to keep in order, and are therefore never used for
practical purposes in the art of electro-metallurgy.
PROPERTIES OF METALS FIT FOR BATTERIES.— In looking to the
above table, it may be asked, " Since lead stands next to copper,
and is so much cheaper, why should it not be used instead?" The
reason is, that there are other properties which a metal, especially
that used as the negative element, ought to possess to fit it for use
in a voltaic arrangement ; such as the power of freely conducting
an electric current, of keeping a bright surface, and not becoming
oxidized ; none of which properties belong to lead. Could that
metal be kept from oxidizing, a very powerful current of electricity
might be obtained by using it with zinc ; but its surface soon gets
coated with an oxide possessing none of the properties of the metal,
and hence the arrangement becomes zinc and oxide of lead, which
produces but a weak current of electricity. These remarks refer
to any metal that is subject to oxidization — an incident which is
often a source of annoyance to the electrotypist when using copper
plates.
Lead slightly amalgamated, and used as the negative metal with
zinc, produces a very constant current for a time.
Lead is also a very bad conductor of the electric current, which
renders it unsuitable for an element in the battery, the negative
metal being considered as only acting the part of a conductor: this
property materially affects the available power of an arrangement
The following table shows the relative Conducting power of the
respective metals :
Silver . . . 120
Copper ... 120
Gold ... 80
Zinc ... 40
Platinum . . 24
Iron ... 24
Tin ... 20
Lead ... 12
We have just stated that a battery composed of zinc and pla
tinum will be more powerful than one composed of zinc and cop-
per, so far as regards their negative and positive tendencies , bui
616 THE PRACTICAL METAL-WORKERS ASSISTANT.
so rnucTi does the conducting power of the negative metal affect
the practical usefulness of a battery, that notwithstanding the fact
that platinum is much more negative than copper, there is so much
of the effective electricity expended in overcoming the resistance
which the inferior conductibility of the platinum offers to the pro-
gress of the current, that a battery of zinc and copper proves to be
a more effective and useful battery for electro-metallurgy than one
made of zinc and platinum. Hence also the reason that iron and
copper, or iron and any other metal, make but an indifferent battery
— iron being a bad conductor ; while lead, which will be seen in
the table, stands lowest in this property, is therefore unfit for bat-
teries.
In fitting up a voltaic arrangement with a negative metal that is
not a good conductor, such as platinum, the closer it is placed to
the exciting liquid, in connection with another metal that is a good
conductor, the better ; because the current obtained will be the
more effectual.
The following experiments will illustrate these remarks with a
few of the common metals used as negative electrodes. There
were, in each battery, six square inches of each metal exposed to the
action of the acid, which was sulphuric acid diluted with 25 parts
of water. The poles were of the same size, of copper, placed in
sulphate of copper; and the quantity of copper deposited was
taken as the data, each trial being of a different length of time :
FIRST, IN ACTION HALF AN HOUR.
BATTERY. DEPOSITED.
Tin and zinc / 1*7 grains.
Copper and zinc . . , 1*8 "
Platinum and zinc . . '5 "
Platinized silver and zinc . 2*0 "
SECOND, IN ACTION TWO AND A-HALF HOURS.
Tin and zinc . . . . 5'9 grains.
Copper and zinc . . . 8*8 "
Platinum and zinc . . . 4-5 "
Platinized silver and zinc * 9'7 "
THIRD, IN ACTION SIXTEEN HOURS.
Tin and zinc .... 64*5 grains.
Copper and zinc . . . 50*5 "
Platinum and zinc . . . 43'0 "
Platinized silver and zinc . 67'3 "
From these few experiments it appears that tin and zinc, when
used for a long time, constitute a very effective battery. It is
very constant in its action, and thus suited for time. It stands
nxjxt to platinized silver. The whole, in nineteen hours, gave
respectively —
DESCRIPTION OF GALVANIC BATTERIES
517
Platinized silver
Tin
Copper .
Platinum
79' grains.
72-1 "
61-1 "
48-0 "
BABINGTON'S BATTERY. — If we look back to the description
given of the voltaic pile (page 489), and the improvement made upon
it by Cruikshanks, we perceive the relation they bear to the pieces
of copper and zinc mentioned in page 510 ; but the relation is mow
apparent in Babington's improvement upon Cruikshank's battery
When working with this battery, it was found that the energy <y
Figs. 545
546.
Fig. 517.
the battery did not depend, as was supposed, upon the extent of
surface of the zinc and copper which were in contact, but upon
the extent of surface of these metals in contact with the liquid
with which the battery was excited ; and that it was sufficient if
the zinc and copper touched each other in a single point ; — pro-
vided that the plates were plunged into the liquid, and that the
copper plate should be exactly opposite to a zinc plate in the same
cell, a space between them. Hence, instead of soldering the zinc
and copper together, as Mr.
Cruikshanks did, it was
enough to effect a communi-
cation by turning over a por-
tion of the copper plate at
the top, and soldering it to
the upper extremity of the
zinc. Thus — c, the copper,
is bent over to touch and be
soldered to the zinc plate z.
For this arrangement, the
wooden trough was divided,
by plates of glass or var-
nished wood, into as many
cells as there were pairs of
zinc and copper. The cells
being filled with the acid, or
exciting solution, the metals
were then placed into them in such a manner that each pair of
518
THE PRACTICAL METAL-WORKER^ ASSISTANT.
zinc and copper plates had a partition between. By this arrange-
ment the zinc of one pair faced the copper of the next pair in the
cell, as shown in Figures 546 and 547. The former represents the
plates immersed in the solution ; the latter, the plates suspended on
a rack over the solution. This arrangement was termed Babing-
ton's Battery.
WOLLASTON'S BATTERY. — Although we have spoken of the
great value of amalgamated zinc for batteries, still at the period
when the arrangement just described was introduced, amalgama-
tion was not known ; and the zinc plates were, therefore, always
liable to be destroyed by the acid. It was, consequently, of im-
portance that no zinc should be exposed to the action of the acid
that was not calculated to give electricity, as the energy of each
pair of plates depends upon the extent of surface of the two metals
exactly opposite to each other. It will be evident that in Babington's
arrangement only one side of the zinc was effective in giving elec-
tricity, while both sides were exposed to the action of the acid. To
obviate this defect, Dr.
Fig- 548. Wollaston caused the cop-
per plate to surround the
zinc, by which the whole
surface of the zinc exposed
to the acid was made effec-
tive in producing electric-
ity, and thereby doubling
its quantity without further cost. The accompanying figure (Fig.
548) shows the manner in which this battery was originally con-
structed.
This improvement, if we except several modifications of con-
struction for the facility of taking the plates asunder for cleaning,
etc., did all for this kind of battery that could be done.
MODIFICATION OF WOLLASTON'S BATTERY NOW IN USE. — Wol-
laston's battery is still generally used in large factories for deposit-
ing metals ; and it is found by experience to be the most convenient
and economical of all the batteries yet contrived. The modifica-
tion we have found to be very suitable, and practically useful, may
be thus described. In the arrangement represented above, when
amalgamated zincs are used, small quantities of amalgam fall from
the zinc plates upon the copper, which not only occasion local
action, but the mercury amalgamates with the copper, spreads over
it, and to a great extent lessens its efficiency ; and as the copper
must be red hot to expel the mercury,
much loss of copper as well as mercury
is the result. To obviate this defect, the
copper is connected above the zinc and
left open at bottom; as, for example, a
thin sheet of copper, of dimensions accord
ing with the size of the cells in the battery, is cut thus: This cop-
per is bent in the middle at b, the ends a a dip into the cells, while
Fig. 549.
j'"'i'i!i';! a
DESCRIPTION OF GALVANIC BATTERIES.
519
c is bent over to connect with the zinc plate of the neighboring
cell, thus:
Figs. 550 551.
The zinc plates are placed between the bent copper a a. The fol-
lowing diagram of a battery of several pairs of plates will illustrate
these observations :
Fig. 552.
z z z z. The zinc plates.
c c c c, Copper plates.
PPP, Partitions of trough,
which are generally made
of thin wood.
ww, Wires from battery.
The zinc and copper are connected together by a binding screw.
To construct this battery the zinc plates are put in first, being
made to slide in grooves, cut in the sides of the trough, the plates
standing in the centre of their respective cells: the copper plates
are put in, and the copper bands marked c are made fast to the
zincs by binding screws, care being taken that the paris where
they are connected are clean and bright, and that the copper and
zinc touch nowhere else. A battery of nine pairs of plates can
be fitted up and made ready for action in ten minutes.
In fitting up batteries of this sort, we are aware that sometimes
great care is taken that the partitions in the trough be perfectly
water-tight, and also formed of Some non-conducting material, such
as glass, or of wood, either pitched or saturated with some non-coii-
ducting substance; but we have found in practice that these pre-
cautions are not required, the principal thing to attend to being,
that the metals should not be allowed to touch, except in their
proper connections.
DEFECTS OF COMMON ACID BATTERIES. — Although we have
spoken thus favorably of the principles upon which Wollaston's
battery is constructed, still as a philosophical instrument it is far
from being perfect: hence the many modifications of it which have
been recommended. Indeed, electro-chemists, since the time of
Volta, have been endeavoring to invent an instrument free from
the defects which attach to Wollaston's — one capable of giving, at
520 " THE PRACTICAL METAL-WORKER^ ASSISTANT.
the same time, a constant and powerful current, abundant, in quan-
tity, and of groat intensity. The success and results of these en-
deavors are so closely connected with, the art of electro-metallurgy,
and the knowledge of them is so essential to a successful prosecu-
tion of the art, that we must not be sparing in our descriptive details.
In operating with a Wollaston's battery, or any other arrange-
ment composed of similar elements, such as zinc, sulphuric or
muriatic acid, and copper, silver or platinum, it will be found that the
current of electricity obtained diminishes in quantity and strength
in proportion to the time of action. This is the result of various
causes :
1st. The hydrogen which is evolved at the surface of the nega-
tive metal in the battery, which we shall say is copper, adheres
with considerable force to the surface of the metal, and consequently
obstructs its superficial influence, so that the quantity of electricity
which the surface of the two metals is calculated to give is much
lessened.
2d. After the battery is in action a short time, a portion of the
sulphate or chloride of zinc, formed in the battery by the solution
of the zinc, becomes reduced upon the surface of the copper. This
reduction is supposed to be owing to the electrolyzation of the zinc
solution by the passage of electricity, but it is, more probably,
caused by a galvanic action upon the copper plate and the solution
in the battery. It generally begins at the lower edge of the copper
plate, and spreads upwards. This weakens the electric current,
both by inducing a galvanic action between the zinc and the cop-
per, upon which it is deposited, and by its tendency to send a cur-
rent of electricity in an opposite direction to the main current, thereby
neutralizing to a great extent the original power of the circle.
3d. When copper is used it becomes gradually covered over with
a thin, black, slimy coating of oxide and other impurities, which
materially affects the regularity and strength of the current: this
is a source of considerable annoyance in working, and necessitates
a regular cleaning of the coppers, which should be done immedi-
ately on being taken out of the battery, by brushing with a hard
hair brush in water; but when the battery has been long in action,
this mode of cleaning is insufficient : the plates will then require
to be rubbed over with a little dilute nitric acid, and then washed.
If the black coating be allowed to dry upon the coppers, they must
then be dipped into strong nitric acid till their surfaces are acted
upon ; or they may be moistened with a little urine, then brought
to a dull red in the fire, and immediately plunged into water; but
in both cases there is a loss of copper. A small quantity of the
black matter, upon being tested, gave oxide of copper, with a trace
of iron, antimony, and lead, which are the general impurities of
sheet copper.
Max, Duke of Leuchtenberg,* has giving the following results
* Progress of General Science, vol. ii.
DESCRIPTION OF GALVANIC BATTERIES. 521
of an analysis of the black matter found upon the copper plate
forming the positive electrode in a copper solution.
Sand 1-90
Antimonv 9'22
Tin . " 33-50
Arsenic 7'40
Platinum . . . . O44
Gold 0-98
Silver 4*45
Lead 0-15
Copper . . . ' . . 9-24
Iron 0-30
Nickle 2-26
Cobalt O8G
Vanadium ..... 0'64
Sulphur 2-46
Selenium 1-27
Oxygen 24-8S
99-9^
An analysis of this sort invests the subject with great interest.
We wish there had also been given an analysis of the copper that
was used as the electrode, and the quantity of black matter obtained,
and the quantity of copper dissolved to yield that product : for the
analysis indicates an amount and diversity of impurities in copper
that has never hitherto been thought of. Both the number and
the proportions are startling. However, it is a known fact, that
the more impure the copper is that is used for a pole, the black
matter is not only more easily, but more abundantly produced.
Another source of weakness to the electric current, and which
affects more or less all batteries of whatever construction, arises
from the action of the acid upon the zinc. The more freely this
action is allowed to proceed the more constant and powerful is the
battery. The acid in combining with the zinc forms a salt, which,
if it adhered to the surface of the plate, would soon stop further
action ; but this salt being soluble in water, is dissolved from the
surface of the plate as soon as formed, allowing a new surface to
be exposed. But water can only dissolve a certain quantity of
the salt, and its power of dissolving decreases as it approaches to
the limit of saturation : hence there is a constant tendency to a
decrease of power in the battery, and if means be not taken to with-
draw the salt of zinc formed, the battery will continue to decrease
in power, till at length it ceases to act. But long before the battery
ceases to act, the presence of sulphate of zinc manifests itself in
several ways, neutralizing the efficacy of the battery. The zinc,
salt, as it dissolves from the plate, being heavier than the acid sola-
tion, falls to the bottom ; hence in a very short time the solution .*
THE PRACTICAL METAL-WORKER'S ASSISTANT.
formed of strata of different densities, and this induces a galvanic
action between the lower and upper portions of the plates, both cop-
per and zinc, and accounts for the deposition of zinc on the bottom
part of the plates, as above referred to. This local galvanic action
between the bottom and top parts of the zinc plate is sometimes so
great when the battery has been long in action, as to double the
thickness of the zinc plate at bottom, while the part near the surface
of the solution is nearly penetrated by the acid ; and when a battery
is formed of a number of pairs, the terminal zincs are those most
affected, the one forming the negative terminal or pole more so
than tho other. We have found a deposition of 6J ounces of zinc
upon the two lower inches of a plate terminal, which measured, in
the solution, six inches by five, the battery having been in opera-
tion but eighteen hours. When this occurs, the quantity of elec-
tricity circulating through the battery is very small. Although
this evil may not proceed to the extent of having quantities of
zinc deposited upon the bottom part of the plates, still the tendency
to deposition which every one who employs a battery must have
observed, as also the more rapid action of the acid on the upper
Earts of the plates, shows that the action of the acid over the sur-
ice of the plate is very irregular, and consequently the quantity
of electricity must be irregular in the same degree, often produc-
ing in the battery an intermittent action.
Various means have been devised for removing the sulphate of
zinc, and adding corresponding quantities of new acid water ; the
most simple and effective of which, according to our experience,
is to make the battery trough much deeper than is required for
the plates, which may be supported either by grooves in the side
of the trough, cut to the proper depth, or by a fillet of wood, or
perforated false bottom ; so that the zinc salt when formed may
fall under the plates, and thus a much longer time elapse before
its presence produces any decidedly bad effect.
There can be no doubt, we think, that some easy means will yet
be devised for carrying off the dense solution of sulphate of zinc,
before it rises to the plates, and for replacing it by acid water from
above, thus giving to the battery a uniformity and steadiness of
action it does not at present possess. There have been many in-
genious contrivances tried for thte purpose by the amateur, but
we have seen* none so simple and economical for manufacturing
purposes, as that referred to.
DANIELL'S BATTERY.— A few years ago, some of the disadvan-
tages now detailed were to a great extent overcome by a very in-
genious arrangement discovered by the late Professor Daniell.
The discovery consists in the separation of the zinc from the
copper by a porous diaphragm, such as bladder, unglazed porce-
lain, etc., and the use of two distinct fluids. The, portion of the bat-
tery containing the zinc is charged with dilute acid as before, but
the portion containing the copper is filled with a solution of sul-
phate of copper. The action in this battery is similar to that
DESCRIPTION OF GALVANIC BATTERIES.
Fig. 553.
described in the ordinary battery ; the zinc is dissolved by the
acid, but the hydrogen, instead of being evolved at the copper
plate, combines with the acid of the sulphate of copper : metallic
copper :s thus set at liberty upon, and combines with, the copper
plate of the battery, not only maintaining but improving its sur
face, during the evolution of a constant cur-
rent of electricity. From the constancy of the
current maintained the battery has been termed
the Constant Battery. The construction of a
single pair is described by Professor Daniell
in the following terms :
"A cell of this battery consists of a cylin-
der of copper 3J inches in diameter, which
experience has proved to afford the most ad-
vantages between the generating and conduct-
ing surfaces, but which may vary in height
according to the power which it is wished to obtain. A mem-
branous tube, formed of the gullet of an ox, is hung in the centre
by a collar, and a circular copper plate, resting upon a rim, is
placed near the top of the cylinder, and in this is suspended, by a
wooden cross-bar, a cylindrical rod of amalgamated zinc, half an
inch in diameter ; the cell is charged with eight parts of water, and
one of oil of vitripl, which has been saturated with sulphate of
copper, and portions of the solid salt are placed upon the upper
copper plate, which is perforated like a collander for the purpose
of keeping the solution always in a state of saturation. The in-
ternal tube is filled with the same acid mixture without the copper.
A tube of porous earthenware may be substituted for the mem-
brane with great convenience, but probably with some little loss
of power.*
A number of such cells may be connected very readily, by attach-
ing the zinc of the one to the copper of
the other, and (as shown in Fig. 554) thus
forming an intensity arrangement of
great power and constancy.
This arrangement of battery is emi-
nently suited to all kinds of electrical
operations, and it may be borne in mind
that it was by operating with this bat-
tery the idea of electro-metallurgy first
occurred. In this battery we see that the evils arising from the
slow liberation of the hydrogen from the surface of the negative
metal, and the deposition of the zinc upon the copper, and also
the blackening of the surface of the copper, are all surmounted.
Nevertheless it is not used to any extent in the art of electro-
metallurgy, it being much less economical than the ordinary bat-
teries, from the quantity of copper salt necessary to keep it in a work-
Fig. 554.
* Daniell's Chemical Philosophy, 2d edition, 1843, p. 504.
52-i THE PRACTICAL METAL-WORKER'S ASSISTANT.
ing condition, and from the necessity of using porous diaphragms,
which speedily wear out. If the diaphragm is made of animal
membrane, the acid very soon destroys it ; and although unglazed
porcelain lasts a little longer, the acid acts upon the alumina, so
that after a few days' working the diaphragm becomes too porous ;
and if the zinc plate touches the porous vessel, a circumstance very
difficult to avoid, there is very soon formed in and upon the porous
surface a deposit of copper which speedily renders the cell useless,
besides producing a loss of copper. The saturation of the zinc
solution, already spoken of, not unfrequently produces the same
effects — the saturated portion of the bottom becomes reduced by
the local action, and thus often a minute point of metallic zinc
touches the cell, and forms a nucleus for a deposit of copper upon
the porous cell, which spreads over the surface very rapidly.
There are always pieces of amalgamated zinc, like fine scales, fall-
ing to the bottom of the cell, which also form nuclei for the deposi-
tion of copper upon the porous cell.
After the cells have been some time in use, if they are laid aside
and allowed to dry, they are very liable to break. Care should be
taken to keep them in clean water till the salts within the pores
are dissolved out ; but if this precaution is taken they may be
preserved for a long time if only used occasionally.
The remarks upon the economy of the arrangement just de-
scribed have reference to its use as an instrument, or separate bat-
tery, for the deposition of a metal in a separate cell (decomposi-
tion cell) ; but not to the arrangement known in electro- metallurgy
as the single cell process, which is simply a mpdification of one
pair of Daniell's arrangement; a description of which, with its
comparative economy, will be given in another part of this treatise.
Professor Daniell says that any depth of cell may be used ac-
cording to the power required, but this cannot be done with equal
advantage, for a large surface of zinc in a cell is not the most
economical, when a great quantity of electricity is required.
GROVE'S BATTERY. — Another battery, constructed upon the
same principle as Daniell's, but differing in the arrangement of the
metals, and the substances used to excite them, was invented by
Mr. Grove, and is known as Grove's Hattery. In this arrange-
ment, platinum is used instead of copper, and strong nitric acid in-
stead of the sulphate of copper of Daniell's bat-
Fig. 555. tery. One pair may be fitted up conveniently
J in a tumbler or jelly-pot. A cylinder of zinc is
placed inside the tumbler ; within this cylinder is
placed a porous vessel, in which is a slip of pla-
tinum either in sheet or foil ; the porous vessel
is filled with strong nitric acid, and the tumbler
with dilute sulphuric acid: a wire is next at-
tached to each metal, and the battery is complete.
When a series of pairs is to be used, the form we have found most
convenient is to arrange the metals in the same manner as we have
DESCRIPTION OF GALVANIC BATTERIES.
525
described -ftr Wollaston's trough (page 518). The zii.3 is formed
in the same shape as shown by Fig. 555. The zinc is placed in the
cell of the trough, and the porous vessel which should be flat is
placed within the zinc, so that the platinum in it may be con
nected with the zinc of the neighboring pair, as represented in
figure 556.
zzz, Are the zinc plates of Fig- 556-
the form of figure 555. s-\ ^ iBf
aaa, Porous cells filled with f^ ^^
nitric acid.
ccc, Plates of platinum
united to the zinc at top by
binding screws.
pp, Are partitions. The di-
visions of the battery trough
need not be water tight, but
merely such as will prevent the zincs from touching one another.
It will be seen that by this means any number of pairs may be
easily arranged. Care, however, must be taken, when fitting up
such an arrangement, that the platinum be kept closely connected
with the zinc by a large surface, otherwise the platinum will be
fused at the connections. A flat piece of wood, with a groove to
fit the zinc, is often made the means of keeping the two metals
together, but we prefer flat binding screws of brass, for if kept
clean they assist the connection, being good conductors. The
fusion of the platinum connections, a practical and often expensive
annoyance, may, however, be completely prevented by coating
about half an inch of the end of the platinum, either with copper
or silver, which is easily effected by the electro-process : the coated
part is then connected with the zinc by any convenient means
without the risk of fusing.
Figure 557 represents a section of Mr. Grove's nitric acid bat-
tery, in a series of four pairs of zinc and platinum. The outer
thick line, A B c r>, is an earthenware trough, which is divided
into four cells. The dotted lines represent four porous vessels, of
a size sufficient to contain about double the quantity of liquid that
is contained between the outer surfaces of the porous vessels and
the earthenware cells. The dark central lines are the plates of
amalgamated zinc ; and the thinner lines, that bend round under
the porous cells, show the position of the platinum foil, which is
attached to the zinc plate by small screws.
This form of battery is also free from some of the objections to
the common battery, but it is seldom or never used in the ordinary
processes of electro-metallurgy. Its advantages over every other
known form of battery are, its great activity of action, and inten-
sity or power of current — a circumstance not generally sought
after by electro-metallurgists. But if it were duly considered that
a battery consisting of three pairs of zinc and platinum is far
more effective than an ordinary battery of ten or twelve pairs
526
THE PRACTICAL METAL- WORK EI^S ASSISTANT.
(although the elements of its construction are more expensive), it
would stand a fair chance of being adopted as the more economical
battery of the two.
Fig. 557.
The porous cells have not the objection of being closed up by
the deposition of metals upon or within them ; but they are affected
by the acids, and by long working they become too porous, the
nitric acid passing through and causing rapid destruction of the
::inc. It wants the constancy of Dani ell's, its quantity declining
:rapidly when long in action — one feature we have often experi-
enced which we have not seen observed by other experimenters.
When working with a Grove's battery of from eight to twelve
pairs, the platinum being six inches by seven inches, after the bat-
tery was in action for four or five hours, during which it dimin-
ished in quantity gradually, all of a sudden it seemed to recover
its energy, giving a quantity and power not much less than it gave
in the first hour, and then declined again rapidly, but occasionally
renewing its vigor for short periods. We have thought it proba-
ble that this reaction may be caused by the formation of nitrate
of ammonia in the rapid decomposition of the nitric acid during
the first action of the battery, which, as it accumulates, may be
reacted upon.
The prevailing and permanent objection to the use of this
arrangement, not only for manufacturing purposes, but for many
experimental purposes, is this, that it emits nitrous fames which
corrode every thing within their reach, and prove very disagreeable
to every person breathing them. For a small single pair of
Grove's battery it is very convenient to use a circular form, in
which case a little cylinder of wood, bored so that its sides be
about Jth of an inch thick, does well for a porous cell, and will
»ast a long time.
BUNSEN'S BATTERY is a modification of Groves' and much used
on the continent for electrical purposes. Carbon is used instead
DESCRIPTION OF GALVANIC BATTERIES. 527
of the platinum, and for convenience it is generally made cylin-
drical. The mode of construction is to form a hollow cylinder by
coking pounded coal in an iron mould, then soaking the coke cyl-
inder in a solution of sugar and calcining a second time, whicb
gives great compactness. The porous cell containing the zinc and
dilute acid is placed in this cylinder, and the whole put into a
glass or stoneware vessel charged with nitric acid ; of course the
coke cylinder and zinc are connected, and thus the battery is com-
pleted.* Nitrous fumes are evolved from this battery also.
SMEE'S BATTERY. — Some of the defects in the common battery
of zinc and copper were much lessened by an ingenious contrivance,
of Mr. Alfred Smee. This gentleman had observed that if the
copper plate of the battery be roughened, either by corrosive acida
or by rubbing the surface with sand paper, its action was made
much more efficient, the rough surface evolving the hydrogen
much more freely. Taking advantage, therefore, of this prin-
ciple, he covered platinum foil with a finely divided black powder
of platinum, deposited by electricity from a solution of that metal,
and used this in place of the copper in the ordinary battery. In-
stead of platinum foil, Mr. Smee soon after adopted silver foil,
which is much less expensive. The method of preparing Jhese
plates is given by Mr. Smee as follows : — " The silver to be pre-
pared for this should be of a thickness sufficient to carry the cur-
rent of electricity, and should be roughened by brushing it over with
a little strong nitric acid, so that a frosted appearance is obtained.
It is then washed and placed in a vessel with dilute sulphuric acid,
to which a few drops of nitro-muriate of platinum has been added.
A porous tube is then placed into this vessel with a few drops of
dilute sulphuric acid ; into this tube a piece of zinc is put, contact
being made between the zinc and silver ; the platinum will, in a
few seconds, be thrown down upon the silver as a black metallic
powder. The operation is now completed, and the platinized
silver ready for use."f A simple method, which obviates the use
of a battery is thus described : lay the silver between two pieces
of sand paper, and press it with a common smoothing iron, then
pull the silver out while under the pressure. The platinum solu-
tion is made very hot, and the silver dipped in it for some time,
which effects the coating.
The nitro-muriate of platinum is easily prepared: take one pan
of nitric acid, and two parts of hydrochloric acid (muriatic acid) ;
mix together and add a little platinum, either as metal or sponge ;
keep the whole at or near a boiling heat ; the metal is then dis-
solved ; forming the solution required.
* A more simple and less expensive modification of this arrangement, is to
put a solid bar of carbon or coke into a porous cell filled with nitric acid,
whioh is placed in a stone or glass jar filled with dilute sulphuric acid, hav-
ing a cylinder of zinc surrounding the porous cell, leaving about one inch of
space between the porous cell and zinc, similar to a Daniell's, forming a mod-
ification of Grove's, having carbon instead of the platinum.
t Smee's Elements of Electro-Metallurgy, 2d edition, p. 24, 1843.
528
THE PRACTICAL METAL-WORKERS ASSISTANT.
Several experiments have been tried with a view to substitute a
cheaper metal than silver to deposit the platinum upon, but not
with much success. Cheap metals have also been coated with
silver by the electro-process, and been used for depositing the pla-
tinum upon. The most successful is a composition metal made of
tin, lead, and a little antimony, rolled into sheet and plated by silver;
this was found very convenient, because it could be easily bent
into any required shape, and it keeps its place without the neces-
sity of fixing in frames as required by thin silver ; nevertheless,
for constant work these plates are found not to present any per-
manent advantage, and have been abandoned ; besides, to give a
sufficient coating of silver, becomes as expensive as silver foil.
Mr. Smee, in constructing his battery, has been guided by the
expense of the silver, and therefore reverses the order of arrange-
ment introduced by Wollaston, by surrounding the platinized silver
with the zinc. Fig. 558 represents a single cell of this form of bat-
tery. A, is the jar containing the solution, z z,
the two amalgamated zinc plates, s, the platinized
silver plate. The whole are suspended by a cross
bar of wood ; and as it is essential to the proper
working of the battery that the plates be always
parallel to one another, the wooden frame is gen-
erally extended round the edge of the thin silver
plate, though it is not so represented in the figure.
One of the clamps at the top of the wooden bar
is connected with the platinized silver plate, and
the other with a pair of zinc plates. Instead of
a glass or stoneware jar, small square troughs,
made of gutta percha, are often used for the
Smee's battery, as they suit admirably, and are
not liable to break.
When intensity of electricity is required, it is necessary to use a
number of such cells, which may be arranged in a wooden frame,
in the manner shown by Fig. 559, where a b represent the two
Fig. 558.
Fig. 559
poles of the battery, and c c the wires by
which the cells are connected with one
another.
A superior form of compound Smee's
battery, contrived by Acland, is repre-
sented in Fig. 560. In this apparatus
the plates are all connected to a frame
that can be elevated or depressed by
means of an iron rod and rachet wheel, so that the plates may be
either partially or entirely immersed in the solution, or raised at
pleasure out of it. The connections are so contrived, that by a
slight alteration the battery is adapted to afford either quantity or
intensity of electric power. It is usually made' to contain six cells,
any number of which can be used at once that a given process may
require. The exciting fluid is contained in an incorrodible stone
DESCRIPTION OF GALVANIC BATTERIES.
529
ware trough, placed in a mahogany box. A battery of this des-
cription, each silver plate of which measures 20 square inches, ha3
sufficient power, when decomposing water, to disengage one cubic
inch of mixed gases in 50 seconds, and will heat to redness 4 inches
of platinum wire.
Letter B in Fig. 560 represents an apparatus for showing the de
Fig. 560.
composition of water into oxygen and hydrogen gas by the voltaic
battery.
It will be observed in Smee's arrangement that there are two
surfaces of zinc, in every pair exposed to the acid, which do not
give off any electricity, but when long in use are much acted upon,
forming a consideration of some value to a manufacturer.
The silver used is very thin, and liable to crack when taken
from its frame, and therefore cannot be made into different con-
structions of battery in the same manner as we can do with cop-
per. It is also liable to have zinc deposited upon its surface when
long in action.
There is we believe no arrangement of battery better known
and more used by amateur electrotypists than Smee's, and there
are probably none better adapted for small operations ; but it has
not been introduced to any extent in the factory. When used iu
series, the advantages it possesses over Wollaston's do not counter-
balance the extra labor and expense attending its use, and many
who have tried it in the operations of the factory have for these
reasons given it up.
Numerous modifications of these different batteries have been
proposed from time to time, intended for different objects, but those
given embrace all that are used for electro-metallurgical purposes.
Owing to the apparent advantages of certain forms of battery, the
following may be referred to :
EARTH BATTERY. — The fact that when a piece of copper and *
530 THE PRACTICAL METAL- WORKER'S ASSISTANT.
piece of zinc are imbedded in the earth and connected by a wire,
there is a current of electricity obtained from them, in the same
way as if they were placed in any battery trough, instantly sug
gested the application of the earth, or what is termed an earth
battery, to the purposes of depositing. We need hardly say these
trials were without success. The electricity obtained in this way
is very weak, depending wholly upon the moisture of the earth,
and the arrangement forming therefore simply a water battery.
We have made electrotypes by this means, and also plated small
articles, but the action or deposition is very slow. We have ob-
tained a greater amount of deposition in five minutes from one
square inch of zinc and copper placed in dilute sulphuric acid,
than from four feet of zinc and copper placed in the earth in the
space of an hour. An earth battery adapted to deposit from 150
to 200 ounces of silver per day, would require acres of land.
In this as in all other forms of battery the deposit is in relation
to the zinc oxidated in the battery ; there would therefore be no
economy in using the earth battery, and to lessen the amount of
surface required by an intensity arrangement, would not alter the
law, but rather add to the expense, as it would require upwards of
100 pairs in the earth to be equal to 3 or 4 pairs of Wollaston's
for the object of depositing ; and would thus be adding to the cost
of depositing one hundred times the equivalent of zinc instead of
four times its equivalent.
MAGNETO-ELECTRIC MACHINE. — Several years ago, Mr. Wool-
rich, of Birmingham, patented a discovery for applying to the
deposition of metals the electricity obtained from magnetism or the
magneto-electric current, instead of voltaic electricity. We have
never had an opportunity of operating with Mr. Woolrich's ma-
chine, nor of seeing it in operation for the purpose of deposition.
We cannot speak of it from experience ; but, from a statement
made at the meeting of the British Association in 1850, by Mr.
Elkington, of Birmingham, who is the proprietor of the patent,
and a gentleman of most extensive experience, it would seem that
he had up to that time never been induced to give up the ordinary
battery in favor of magnetism or any other suggested improve-
ment. We understand however that this means of obtaining the
electricity for the purposes of electro- metallurgy has recently been
much improved, by forms of magnets, etc., patented by Mr. Mill-
ward, and described by him as follows : " The first branch of the
improvement is carried into effect by the employment of an electro-
magnet formed by a current of electricity produced from a
magneto-electric machine, instead of that generated in a voltaic
battery; and such an electro-magnet may be very advantageously
used for magnetizing large bars of steel, or for producing very
powerful magnets. Any of the known forms of magneto-electric
machines will serve thus to convert a bar of "steel to an electro-
magnet, but the patentee prefers to use one composed of four,
eight, or any other number of permanent magnets, having double
DESCRIPTION OF GALVANIC BATTERIES. 531
the number of armatures, and coiled with strong wire of about 60
feet in length. The machine about to be described has been found
to answer well in practice. In this machine the steel magnets are
composed of eight plates of a U form, weighing about 30 Ibs,
each plate, and there are eight such compound magnets, all the
north poles of which are arranged on one side of the machine,
and the south poles on the other side, although this precise ar-
rangement is not essential, and may be varied. The armatures are
of soft iron, weighing about 15 Ibs., and are coiled about with 60
feet of copper wire of No. 4 gauge, and insulated in the usual
manner. The armatures revolve in a brass wheel, and are caused
to pass as near to the poles of the magnets as practicable, the com-
mutator or break acting on the whole eight magnets at the same
instant, so that the current of electricity shall always pass in one
direction, and the surface of the whole of the 64 plates be in com-
bination at the same time. The bar of soft iron used as the
electro-magnet with this machine weighs about 500 Ibs., and is
coiled with bundles of about 30 copper wires of No. 16 gauge,
and about 60 feet in length (the bundles are formed by binding a
series of uncovered wires together into one covered strand or
bundle), and the power of the electro-magnet will depend upon the
power of the permanent magnets used in the machine, both as to
the weight it will support from a keeper, and as to its capability
of rendering bars of steel permanently magnetic by contact there-
with. It will ' therefore be evident that by having two sets of the
permanent magnets, and changing them in such machine, their
supporting power may be increased by continued charges or passes
from the electro- magnet thus produced. In one form of electro-
magnetic machine represented and described under the second
head of the invention, the steel bars or permanent magnets are
eight in number (these bars may be of cast or soft iron, but when
soft iron is employed, bars of steel permanently magnetized will
have to be used in conjunction with them), of a U form, and ar-
ranged around a circle with their poles pointing towards the centre.
Each arm of each of the magnets has attached to it straight bars
of steel, also rendered permanently magnetic (of which any desired
number, and of any length or size, may be employed, according to
the strength of magnet required), which are so placed as to be out
of the influence of the armatures when the latter are revolving.
The poles of the U-shaped magnets are, on the contrary, as nearly
as possible in contact with the armatures which revolve within the
circle formed by them, either between the poles or in front of them.
Instead of the bars which form the circle being of steel and mag-
netized, they may be made of soft iron, and depend for their mag-
netism upon the magnetic bars before named placed around them.
In another form of machine both the magnets and armatures are
stationary, and the commutator alone has motion between the poles
of the horse-shoe magnets and the armatures, being mounted on a
spindle and caused to revolve by a band from some driving ma-
532
THE PRACTICAL METAL-WORKER'S ASSISTANT.
chinerj . The commutator, or break-piece, is composed of a brass
centre, with four radial arms of soft iron, either solid or formed
of two or more plates." — See Repertory of Patent Inventions, *vol. 18,
for 1851, and Sketches therein.
The quality of these machines for depositing depends much upon
their sustaining power. Eight of these sets of plates or magnets,
containing altogether about 12 cwt. of steel, in a proper state of
working, are said to form a battery capable of depositing from 12
to 20 ounces of silver per hour, but it is not stated, however, upon
what extent of surface this takes place. The relative economy of
these magnets over the galvanic battery has not been so great as
to recommend their general adoption. We have, however, no
doubt that, as such a machine gives electricity of great intensity, it
may be superior to the galvanic battery for some purposes, and
may give properties to the deposited metals which the ordinary
battery does not.*
Before concluding the description of batteries, we may briefly
notice one or two little conveniences which are indispensable to the
operation. The first of these is what are termed binding screws, by
which the parts of batteries, as we have shown by numerous figures,
are connected together, or by which their poles are connected to
the objects through which the voltaic current is to be passed. They
are usually made of brass, and of various forms, according to the
shape of the objects that are to be connected.
Figures 561 to 566 represent some of the most useful kinds; Fig.
Fi 561 is used to connect
561 562 563 564 565 566. wires together; Figs 563
and 565 are required for
Smee's battery (see Fig.
559) ; Fig. 565, to con-
nect the plates of Grove's
battery (Fig. 557); Figs.
563 and 564 are used for
Daniell's battery; the latter for connection with a zinc rod, the
Figs. 567
568.
* For some particulars of the working of electro-magnetic machines, see
Hhaw'a Manual of Electro-Metallurgy, 2d edition. 1843
ELECTROTYPE PROCESSES. 533
former to bind plates together. In all cases, the parts that touch
the surfaces to be connected must be perfectly clear and bright.
In many cases, when a complicated apparatus has been put
together, it is desirable to ascertain whether the connections are
all perfect. This is best determined by means of a galvanometer,
two varieties of which are represented by Figs. 567 and 568.
J
CHAPTER XXYL
*-
ELECTROTYPE PROCESSES.
•
SINGLE-CELL OPERATIONS. — We shall now proceed to detail
the process of electrotyping, the materials for which are of the
most simple nature. Let us suppose that the object of the student
is to copy a copper medal — for example, the side of a penny-piece.
Dissolve a quantity of the crystals of sulphate of copper in any
convenient vessel; if distilled water can be had, the better. This
is conveniently done by suspending the crystals in a coarse cloth
on the surface of the water, or the crystals may be put into the
water, and well stirred, till dissolved ; crushing the crystals facili-
tates their solution. The water should be kept cold and be fully
saturated with the salt, and the solution allowed to stand untouched
for several hours. This last precaution is not always essential, but
only necessary when the copper solution is not perfectly clear and
transparent.
The sulphate of copper of commerce has often a large quantity
of iron in it, a portion of which becomes per-oxidized, and will
precipitate or fall to the bottom of the solution on standing ; in-
deed, when it is known that the salt contains much iron, it is best
to crush the salt very fine, and expose it to the air for some time ;
when dissolved, after this exposure, a great quantity of iron will
settle at the bottom of the solution, which should be carefully
decanted and the last portion filtered. The clear solution should
now have about one-fourth of its quantity of water added to it, as
a completely saturated solution is not the best. A newly -formed
solution does not deposit so freely as one that has been in use for
some time. The addition of a few drops of sulphuric acid, or, what
we have found better, a little sulphate of zinc — about one ounce to
the pound of sulphate of copper — improves the condition of a new
solution.
Next, put the solution of sulphate of copper into the vessel in
tended for use, say it is a large jelly-pot, in which let a vessel of
unglazed porcelain (porous vessel) be placed, filled to within half
an inch of the mouth with a mixture of 24 parts water and 1 sul-
phuric acid, taking care that the copper solution is of the same
depth as the solution in the porous cell.
£ 54: THE PKACTICAL METAL -WORKER'S ASSISTANT.
PREPARATION OF THE COIN. — A fine copper wire must now bo
put round the edge of the coin and fastened by twisting. Then
cover the back part, upon which the deposit is not required, with
beeswax or tallow, or, what is better, imbed the back of the coin
with gutta percha. Have the fore part or face well cleaned, and
the surface moistened with sweet oil, by a camel's hair pencil, and
then cleaned off by a silk cloth, till the surface appears dry ; or,
instead of oil, the surface may be brushed over with black lead, which
will impart to it a bronze appearance. The use of the oil or black
lead is to prevent the deposit adhering to the face of the coin. A
very common and excellent method to prevent the copper deposit
adhering to the copper mould is this : — Take a gill of rectified
spirits of turpentine, and add to it about the size of an ordinary
pea of beeswax. When this is dissolved, wet over the surface of
the mould with it, and then allow it to dry : the mould is then
ready to put into the solution. Medals taken from moulds so pre-
pared retain their beautifully bright color for a long time. But
when fine line engravings are to be coated, the little wax dissolved
in the turpentine may be objectionable ; so also is black lead, for
both have a tendency to fill up the fine lines. In this case, let the
wash with turpentine be wiped off by a silk handkerchief, instead
of drying it : but for ordinary medals this objection will scarcely
apply. This being done, the opposite end of the copper wire
round the penny-piece is to be connected with a piece of amalga-
mated zinc, either by means of a binding screw or a hole in the
zinc. Then place the zinc in the acid within the porous cell, and
put the penny-piece into the copper solution : bring the face of the
coin parallel to the zinc, at the distance of about half an inch or
one inch from the porous vessel. Deposition immediately begins,
and the metal thickens according to the length of time the action
is kept up. In about twenty-four hours, the deposit will be of the
thickness of a common card, and it may then be taken off. The
zinc is to be brushed and washed, before it is put aside. The wire
round the coin is now to be untwisted, and by a slight turn will
come off easily. The deposit is also easily separated from the
mould, which will be a perfect counterpart of the face of the penny-
piece.
This mould is next to be treated exactly as described for obtain-
ing it from th'e penny-piece, and the deposit from it will be a fac-
simile, of one side of the penny -piece. With care, any number of
duplicates may be taken from this mould.
It need hardly be remarked, that as copper is deposited the
solution becomes proportionally exhausted, and in a short time the
current of electricity passing will be too much for the strength of
the solution, which will then give a deposit of a sandy consistence,
without tenacity.* It is therefore necessary, while the deposition
is going on, to suspend some crystals of sulpha'te of copper at the
* See Laws of Deposition, page 20.
ELECTROTYPE PROCESSES.
535
top of the solution, which, as they dissolve, will maintain its
strength.
FORMS OF APPARATUS. — It will be observed that no particular
form of apparatus is required for electrotyping, but certain modi-
fications may be adopted for convenience and economy. As every
portion of the zinc in the acid is capable of giving off electricity,
by placing the cell that contains the zinc in the centre of the cop-
per solution, moulds may be suspended on each side of that cell.
We have also observed that the zinc plate should not be allowed
to touch the cell, as the copper will be reduced upon it and the
cell destroyed. To avoid this, the zinc may be suspended by a
small wooden peg, put through it and made to rest upon the edges
of the cell. Figures 569, 570, 571, 572, represent several convenient
forms of apparatus for electrotyping.
Figs. 569
570
571.
Fig. 572.
Fig. 572 is a form of the apparatus which the author has used
for many years with great success, being both
cheap and effective, a is a large jelly-pot1 hold-
ing the copper solution ; b is a flat porous cell,
about 4 inches square and half inch wide; z
the zinc plate. Amalgamated metals may be
suspended upon both sides, and the strength
of the solution is maintained by suspending a
few crystals of the salt in a little cloth bag
upon the surface of the solution.
Instead of porous vessels made of earthenware, a bladder may
be -used, in which the acid and zinc are placed. We have also
seen a vessel divided by a porous partition, being either a plate of
biscuit porcelain, plaster of Paris, very thin sycamore wood, or
dressed skin. The porcelain, as before mentioned, is the best :
plaster is too porous, and the solution soon destroys it : wood is
too close, and the deposit is consequently very slow : skin does
very well for a short time, but it is soon destroyed. When porous
cells were not convenient, we have made electrotypes by wrapping
the zinc plates in two or three folds of stout cartridge paper, moist-
ened with a solution of salt, and placing this in the copper solution
with the mould. Of course, this is only to be adopted when a
porous vessel cannot be obtained. The paper lasts but a short
536 THE PRACTICAL METAL-WORKER'S ASSISTANT.
time, and has, therefore, to be frequently renewed ; besides which,
there is always a deposit of copper upon the paper, thus occasion-
ing a loss.
Common coarse garden -pots answer excellently for porous vessels,
closing the aperture at bottom by a cork.
The precautions that have been given (see Daniell's Battery, p.
39), as to the preserving of the porous cells when not in use, are
applicable to the cells or partitions used in these processes, which,
when not in use, should be kept in water, or should not be allowed
to dry until they have been in water long enough to dissolve out
the salts that were within the pores of the cell ; otherwise the salts
crystallize, and either crack the cell or cause it to scale off' in small
pieces. Porous cells, when not thoroughly washed and freed from
salts, if laid aside for a few days, often thrown out an efflorescence,
or crystalline growth, like mould, of a soft silky texture, and from
one-half to one inch in length. An analysis of this efflorescent
matter gave
Oxide of zinc .... 39-6
Sulphuric acid . . . . 26'0
Water 34'2
99-8
COMPARATIVE VALUE OF EXCITING SOLUTIONS. — We have
recommended the porous cell being filled by dilute sulphuric acid,
which we consider best ; but other saline solutions will serve the
same purpose : solutions of common salt, sal ammoniac, sulphate
of zinc, have been recommended, and each has been called best in
its turn. The following results of experiments with these solu-
tions in the porous cell will show their relative qualities, and enable
the student to judge for himself. The size of the zinc plate in the
cell used in these experiments measured 6 inches by 6 inches ; the
copper plates upon which the deposits were formed were the same
size; the solution of copper was kept at the same strength; the
time that each was in solution was 16 hours.
ELECTROTYPE PROCESSES.
537
Solution in porous Cell.
Zinc
dissolved.
]
Copper deposited.
Sal ammoniac.
OZ.
dwt.
gr-
OZ.
dwt.
gr.
Saturated solution . .
1
5
14
1
2
12
1 part saturated solution
1 part water ....
1
8
5
1
3
10
1 part saturated solution
8 parts water ....
i
0
12
13
0
10
17
Common /Salt.
Saturated solution . .
0
16
3
0
14
12
1 part saturated solution
1 part water . . . .
•
0
18
9
a
17
8
1 part saturated solution
3 parts water ....
!
1
0
5
0
19
16
I
• i
Sulphate of Zinc.
I
Saturated solution . .
1
3
18
0
19
0
1 part saturated solution
1 part water ....
I"
1
0
8
0
19
18
1 part saturated solution
3 parts water ....
I
0
14
16
0
14
8
Sulphuric Acid.
1 part to 8 of water .
.
3
1
6
i
4
8
1 part to 16 of water
.
2
11
8
2
1
8
1 part to 24 of water
• •
2
7
3
2
5
6
How OFTEN SOLUTIONS SHOULD BE CHANGED AND ZINC AMAL-
GAMATED.— Students have often put this question to us : How often
should the solution in the cell be renewed, and the zinc plate be
amalgamated ? The following are the results of many trials made
to ascertain the facts necessary to answer this inquiry. The "zinc
plates used were nearly one foot square, and the copper plate upon
which the deposit was made was of the same size as the zinc plates.
In the first series the zinc plates were not taken out either to
brush or re-amalgarnate, neither were the solutions renewed during
the time specified.
2 Ib. common salt in
gallon of water
one
2 Ib. sulphate of zinc in one
gallon of water
1 Ib. sulphuric acid to 24
of water
( 24 hours
A 48 hours
( 60 hours
24 hours
48 hours
60 hours
24 hours
48 hours
Copper
Zinc
deposited.
• dissolved.
OZ.
dwt.
07,.
dwt.
12
9
12
17
17
13
20
17
24
15
34
3
9
13
9
18
16
4
17
10
23
10
24
8
15
17
17
15
27
16
32
3
538 THE PRACTICAL METAL- WORKER'S ASSISTANT.
From these results it is evident that the best and most economi-
cal manner of treating the solution and the zinc would be to renew
the solution every 24 hours, as the second 24 hours do not give,
without renewal, above half the deposit of the first 24. hours, while
the waste of zinc is very little less than in the first.
The next series of experiments was with the same zinc and the
same kind of solutions, but the zinc was taken out every 24 hours,
and brushed, but not re-amalgamated, and put back again with new
solution in the porous cell.
Copper Zinc
deposited. dissolved,
oz. dwt. oz. dwt.
Salt and water . 4 days of 24 hours . 49 16 51 8
Sulphate of zinc . 4 days of 24 hours . 47 14 48 9
Acid and Water . 3 days of 24 hours . 48 13 53 7
These results give the most ample reply to the question so often
put, and will guide the manufacturer as well as the student in his
operations, whether time or material be of the greatest consequence
to him.
We may remark that the sulphate of zinc solution does not
require renewal, but simply that we half empty the cell and refill
it with water. The sulphate of zinc poured out being nearly satu-
rated, may be crystallized, and will serve for other electro-metal-
lurgical operations.
MAKING OF MOULDS. — The directions giving for obtaining a
mould from a penny-piece, by deposition, are applicable to taking
moulds from any metallic medal, engraving, or figure that is not
undercut ; and for depositing within the moulds so produced. On
the first discovery of this art, the electrotypist was confined to
metallic moulds, as the deposition would not take place except
upon metallic surfaces; but the discovery that plumbago, or black
lead polished, had a conducting power similar to that of metal, and
that the deposit would take place upon its surface with nearly the
same facility as upon metal, freed the art at once from many of its
tranfmels, and enabled the operator to deposit upon any substance
— wood, plaster of Paris, wax, etc. — by brushing over the surface
with black lead. • It obliged the electro-metallurgist, however, to
render himself expert in the art of moulding, since no good elec-
trotype can be obtained without a perfect mould. We shall, for
this reason, endeavor now to give such instructions as will enable
the student to make good moulds after a very short practice ; but
we need hardly add, that in this as well as in every operation,
however plain may be the instructions and easy the manipulations,
practice is necessary to ensure success ; so that the student ought
not to lose patience should his first attempt not succeed to his
wishes. The substances used for taking moulds from objects to
be copied by electrotype are beeswax, stearine, plaster of Paris,
and fusible metal ; recently; gutta percha has been very success-
fully used. The articles to be copied are generally composed either
ELECTROTYPE PROCESSES. 539
of plaster of Paris or metal. Suppose, in the first place, tlie article
to be copied is of metal, and a mould is to be taken from it in wax
or stearine. The latter we have not found to answer well alone;
when used it should be mixed with wax, about half-and-half.
PREPARATION" OF WAX. — Whether the beeswax have stearine
in it or not, it is best to prepare it in the following manner : — Put
some common virgin wax into an earthenware pot or pipkin, and
place it over a slow fire ; arid when it is all melted, stir into it a
little white lead (flake white) — say about one ounce of white lead
to the pound of wax; this mixture tends to prevent the mould from
cracking in the cooling, and from floating in the solution: the mix-
ture should be re-melted two or three times before using it for the
first time.
To TAKE MOULDS IN WAX. — The medal to be copied must be
brushed over with a little sweet oil: a soft brush, called a painter's
sash tool, suits this purpose well : care must be taken to brush the
oil well into all parts of the medal, after which the superfluous oil
must be wiped off with a piece of cotton or cotton wool. If the
medal has a bright polished surface, very little oil is required, but
if the surface be matted or dead, it requires more care with the oil.
A slip of card-board or tin is now bound round the edge of the
medal, the edge of which slip should rise about one-fourth of an
inch higher than the highest part on the face of the medal: this
done, hold the medal with its rim a little sloping, then pour the
wax in the lowest portion, and gently bring it level, so that the
melted wax may gradually flow over ; this will prevent the forma-
tion of air bubbles. Care must be taken not to pour the wax on
too hot, as that is one great cause of failure in getting good moulds ;
it should be poured on just as it is beginning to set in the dish.
As soon as the composition poured on the medal is set (becomes
solid), undo the rim, for if it was allowed to remain on till the wax
became perfectly cool, the wax would adhere to it, and being thus
prevented from shrinking, which it always does a little, would be
liable to crack. Put the medal and wax in a cool place, and in
about an hour the two will separate easily. When they adhere,
the cause is either that too little oil has been used, or that the wax
was poured on too hot.
EOSIN WITH WAX. — Eosin has been recommended as a mixture
with wax; mixtures of which, in various proportions, we have used
with success ; but when often used, decomposition, or some change
takes place, which makes the mixture granular and flexible, ren-
dering it less useful for taking moulds. When rosin is used, the
mixture, when first melted, should be boiled, or nearly so, and
kept at that heat until effervescence ceases ; it is then to be poured
out upon a flat plate to cool, after which it may be used as de
scribed.
MOULDS IN PLASTER. — If a plaster of Paris mould is to be taken
from the metallic medal, the* preparation of the medal is the same
as described above ; and when so prepared with the rim of card-
510
board or tin, get a basin -frith as much water in it as will be suffi-
cient to make a proper sized mould (a very little experience will
enable the operator to know this), then take the finest plaster of
Paris and sprinkle it into the water, stirring it till the mixture
becomes of the consistence of thick cream; then pour a small por-
tion upon the face of the medal, and, with a brush similar to thai
used for oiling it, gently brush the plaster into every part of the
surface, which will prevent the formation of air-bubbles ; then pour
on the remainder of the plaster till it rises to the edge of the rim :
if the plaster is good, it will be ready for taking off in an hour.
The mould is then to be placed before a fire, or in an oven, until quite
dry, after which it is to be placed, back downwards, in a shallow
vessel containing melted wax, not of sufficient depth to flow over
the face of the mould, allowing the whole to remain over a slow
fire until the wax has penetrated the plaster, and appears upon the
face. Having removed it to a cool place to harden, it will soon be
ready for electrotyping. If the mould is large and the plaster
thick, the wax may be put upon the surface, and only as much as
will penetrate a small way into the plaster. In both these instances
the wax used is generally lost, and there is always liability of the
copper solution passing through, and causing what is termed sur-
face deposit, making the face of the medal rough. We may remark
that, although occasionally there may be a very good electrotype
obtained from a plaster mould, still they are in general very in-
ferior ; as the saturating of the plaster has a tendency to blunt the
impression, and the wax used for the purpose of saturation becomes
expensive. It may be partially recovered by boiling the plaster
in water: the wax melts out, and is obtained when the water cools
Plaster should not be used for moulds where wax can be employed,
being neither so good nor so economical ; but there are cases in
which the moulds being very large, the use of plaster is unavoid-
able.
MOULDS IN FUSIBLE ALLOY. — The next means of taking moulds
is by fusible metal. This name is given to alloys of two or more
metals which melt at a very low temperature ; it suits the purpose
of taking moulds of small objects very well. The following are
examples of such compositions :
Tin. Lead. Bismuth. Zinc.
1120
1230
1011
These all melt at a" temperature below that of boiling water.
The ingredients are melted together in an iron ladle, poured out
upon a flat stone, broken up, and re-melted in the same way two
or three times, in order that they may be thoroughly mixed. The
medal from which the mould is to be taken is prepared in the
name manner as described for wax.
The fusible alloy is melted and poured into a saucer, or, what
ELECTROTYPE PROCESSES. 541
does better, a small wooden tray. The operatoi now watches till
it cools down into a semifluid state, or to the poin^ of setting, when
he brings the medal suddenly upon it, face downwards, and holds
it there until the alloy has fairly set ; he then allows it to cool, and
undoes the slip around the medal, from which the mould will easily
separate. The height of the slip of paper above the surface of
the medal determipes, of course, the thickness of the mould. The
beginner very seldom succeeds in his first attempts at making
moulds in fusible alloy ; but as a little experience teaches more
than the reading of an essay upon the subject, he will soon find
both his patience and labor rewarded with gratifying success.
Some of the finest moulds are taken by this process, but, from the
constant loss of the materials by oxidation, etc., it is expensive, so
that its use amongst electro- metallurgists is very limited.
MOULDS IN GUTTA PERCHA. — Gutta percha, as a material for
moulding, serves the purpose most admirably. We have seen
moulds of this substance equal if not superior to any that we ever
saw taken in wax, and of a depth of cutting which it would have
been very difficult to have taken in wax. The method adopted for
taking moulds is to heat the gutta percha in boiling water, or in a
chamber heated to the temperature of boiling water, which makes
it soft and pliable. The medal is fitted with a metallic rim, or
placed in the bottom of a metal saucer with a cylindrical rim a
little larger than the medal ; the medal being placed back down, a
quantity of gutta percha is pressed into the saucer, and as much
added as will cause it to stand above the edge of the rim. It is
now placed in a common copying-press and kept under pressure
until it is quite cold and hard. The impressions taken in this way
are generally very fine. When the medal is not deep cut a less
pressure may suffice, but when the pressure is too little the im-
pression will be blunt.
Gutta percha takes a coating of black lead readily, and the de-
posit goes over it easily.
A mixture of gutta percha and marine glue has been recom
mended for moulds as superior to gutta percha alone. We have
not had an opportunity of using this mixture, but have every con-
fidence in the recommendations given of it.
MOULDS FROM FERNS, SEA-WEED, ETC. — A method of taking
impressions of fern-leaves and sea-weeds has recently been pro-
posed by Dr. F. Branson, in the Athenaeum. It is thus described:
"A piece of gutta percha, free from blemish, and the size of the
plate required, is placed in boiling water. When thoroughly
softened it is taken out and laid flat upon a smooth metal plate
and immediately dusted over with the finest bronze powder used
for printing gold letters. The object of this is threefold — to dry
the surface, to render the surface more smooth, and to prevent ad-
hesion. The plant is then to be neatly laid out upon the bronze
surface and covered with a polished metal plate either of copper
or of German silver. The whole is then to be subjected to ari
542 THE PRACTICAL METAL-WORKERS ASSISTANT.
amount of pressure sufficient to imbed the upper plate in the gutta
percha. When the gutta perch a is cold, the metal plate may bo
removed and the fern gently withdrawn from its bed. A beauti-
ful impression of the fern will remain." . An electrotype may b*
deposited upon the bronzed or black leaded gutta percha.
We have seen many electrotype leaves done by this method,
which were certainly very pretty as electrotypes, and the process
is well adapted for flat leaves ; but the pressure required renders
it unsuitable for some kinds of leaves — indeed, it destroys the
natural forms of the greater number both of leaves and sea- weeds.
The products of the process cannot, indeed, be compared with
those electrotype leaves the moulds of which are taken by wax.
The great merit of the process is its ease and simplicity. The
method given for taking the mould of the leaf is suitable for any
kind of flat mould in gutta percha. The mould of a leaf may be
taken in plaster by placing the leaf upon dry sand and pressing
the sand under and on each side to fill up the spaces under the
leaf so as to bear the pressure of the plaster, putting a collar of
paper round the sand to prevent its yielding, and then pouring the
plaster over the whole. When the plaster is set, the leaf is re-
moved and the plaster trimmed round with a knife. This also has
its difficulties ; for when leaves have hairs upon them they stick
into the plaster. The method of taking moulds of leaves in wax
is by holding the leaf in the hand and brushing a thin layer of
melted wax over the surface to be moulded ; allowing this to
harden, and then brushing on another layer — and so on until the
wax is sufficiently thick to suffer handling. The leaf is then gently
drawn off the wax, which is to be black -leaded, and put into the
electrotype apparatus to receive the coating of copper. A type
of the leaf is by this means obtained with all its natural convo-
lutions.
NATURE PRINTING. — A further improvement upon making
moulds of leaves and other vegetable objects, has been practised
by an eminent firm in London. The leaf is carefully dried and
laid upon a smooth piece of milled lead, which is placed between
two steel plates, and passed between rollers, these press the leaf
into the lead, and produce a complete mould. Copies from this
may be taken with gutta percha or electrotype. Printed impres-
siojis of leaves, sea weed, and such like objects, prepared in this
way, may be seen in an excellent work published by Bradbury
and Evans, and a full detail of the process, with specimens, will be
found in the proceedings of the Royal Institution for 1854:.
CASTING OF REPTILES, ETC. — Imbed the subject in a mould made
of four parts of plaster of Paris, one of unburnt lime powder, and
one of Flanders brick-dust. Dry the mould carefully, then make
it red hot, and burn the subject out of it, taking care to free the
mould from the ashes. Fusible metal may be cast in this mould,
and then be covered with copper, from which the alloy may be
afterwards melted, or a wax model may be taken of the object,
ELECTROTYPE PROCESSES. 543
pouring tha wax in just bafore setting. In neither case must the
mould be melted until after the model, whether of alloy or wax,
is taken, whan the whole is placed in wat^r, the lime causes the
mould to dissolve or break up, and tha figure modelled within it
may be taken and covered with copper. Flowers, insects, lizards,
and other little animals may be typed in this way. In all these
processes, perseverance and care are the best cures for little
difficulties.
WAX MOULDS FROM PLASTER. — If the object, which we assume
to be a medal, from which the mould is to be taken, be composed
of plaster of Paris, and the mould to be taken is in wax, the first
operation is to prepare the plaster medal. Some boiled linseed -
oil, such as is used by house painters, is to be laid over the sur-
face of the. medal with a camel's hair pencil, and continued until it
is perfectly saturated, which is known by the plaster ceasing to ab-
sorb any more of the oil. This operation succeeds best when the
rnedal is heated a little. The medal should now be laid aside till
the oil completely dries, when the plaster will be found to be quite
hard, and having the appearance of polished marble ; it is, conse-
quently, fit to be used for taking the wax mould, which is done in
the same manner as we have described for taking a wax mould
from a metallic medal.
Many prefer saturating the medal with water : this is best done
by placing the medal back down in the water, but not allowing it
to flow over the face ; the water rises, by capillary attraction, to
the surface of the medal, rendering the face damp without being
wet. The rim being now tied on the plaster medal, the melted
wax is poured upon it. This method is equally good, but liability
to failures is much greater, caused generally by the wax being
too hot.
The plaster medal may also be saturated with skimmed milk
and then dried ; by repeating this twice, the plaster assumes on the
surface an appearance like marble, and may be used for taking
wax moulds.,
MOULD OF PLASTER FROM PLASTER MODELS. — When a plaster
mould is to be taken, the face of the model is prepared differently
to that described, in order to prevent the adhesion of the two
plasters. The best substance we have tried for this purpose is a
mixture of soft soap and tallow, universally used by potters for
preparing their moulds, and called by them lacquer. It is pre-
pared in the following manner : — half-a-pound of soft soap is put
into three pints of clean water, which are set on a clear fire, and
kept in agitation by stirring ; when the mixture begins to boil, add
from one ounce to an ounce and a-half of .tallow, and keep boiling
till it is reduced in bulk to about two pints, when it is ready for
use. The surface of the medal must be washed over with this
lacquer, allowing it to absorb as much as it can, when it assumes
the appearance of polished marble ; it is now prepared with a rim
of paper, and the mould taken as directed for taking plaster
544 THE PRACTICAL METAL-WORKER'S ASSISTANT.
moulds from metallic medals. When hardened, they will separate
easily. — Wetting the plaster model with a solution of soap before
taking the cast will do, or, if the plaster model has been saturated
with oil or milk, it has only to be moistened with sweet oil the
same as a metal model.
FUSIBLE ALLOY FROM PLASTER. — If a mould of fusible metal
be required from a plaster medal, the plaster may be saturated
either with boiling oil or the soap and tallow lacquer, and the
mould taken in the same manner as from a metallic medal.
COPPER MOULDS FROM PLASTER. — Many electro-metallurgists
prefer taking a mould in copper when the medal is of plaster of
Paris. This is done by the electrotype process ; the plaster model
is saturated with wax over a slow fire, as already detailed, and then
prepared for taking an electrotype in the usual manner (see page
534). We need hardly mention that the model in this case is de-
stroyed ; but, notwithstanding, in the case of plaster models, to
take a copper mould is the most preferable, as it may be repaired
in case of slight defect, and it may be used over and over again
without deterioration. ,
When an electrotype is required of a model that is undercut, or
of a bust or figure, the process which we have described will not
answer, as the mould cannot separate from the model. In such
circumstances the general method of proceeding is to part the
mould in separate pieces, and then join these together. The
material used for this purpose is plaster of Paris. The operation,
however, to be well done, requires a person of considerable ex-
perience.
ELASTIC MOULDING. — The process patented by Mr. Parks for
taking a mould of any kind of model in one piece, is excellently
adapted for the electrotypist. The material is composed of glue
and treacle. Twelve pounds of glue is steeped for several hours
in as much water as will moisten it thoroughly ; this is put into a
metallic vessel, which, is placed in boiling water as a hot bath.
When the glue falls into a fluid state, three pounds of treacle are
added, and the whole is well mixed by stirring. Suppose, now,
that the mould of a small bust is wanted, a cylindrical vessel is
chosen so deep that the bust may stand in it an inch or so under
the edge. The inside of this vessel is oiled, a piece of stout paper
is pasted on the bottom of the bust to prevent the fluid mixture
from going inside, and if it is composed of plaster, sand is put in-
side to prevent it from swimming. It is next completely drenched
in oil and placed upright in the vessel. This done, the melted
mixture of glue and treacle is poured in till the bust is covered to
the depth of an inch. The whole must stand for at least twenty-
four hours, till it is perfectly cool throughout — after which it is
taken out by inverting the vessel upon a table, when, of course,
the bottom of the bust is presented bare. The 'mould is now cut
by means of a sharp knife, from the bottom up the back of the
bust to the front of the head. It is next held open by the opera-
ELECTROTYPE PROCESSES. 545
tor, when. an assistant lifts out the bust and the mould is allowed
to reclose. A piece of brown paper is tied round it to keep it
firm. The operator has now a complete mould of the bust in one
piece ; but he cannot treat it like wax moulds, as its substance is
soluble in water, and would be destroyed if put into the solution.
A mixture of wax and rosin, with occasionally a little sue£ is
melted and allowed to stand till it is on the point of setting, when
it is poured carefully into the mould and left to cool. The mould
is then untied and opened up as before ; the wax bust is taken out ;
and the mould may be tied up for other casts. Besides wax and rosin
there are several other mixtures used — deer's fat is preferable to
common suet, stearine, etc. The object is to get a mixture that
takes a good cast and becomes solid at a heat less than that which
would melt the mould.
MOULDING OF FIGURES. — If the model or figure be composed
of plaster of Paris, a mould is often taken in copper by deposition.
The figure is saturated with wax, as described for a medal, and
copper deposited upon it sufficiently thick to bear handling with-
out damage when taken from the model. The figure with the
copper deposit is carefully sawn in two, and then boiled in water,
by which the plaster is softened and easily separated from the cop-
per, which now serves as the mould in which the deposit is to be
made. It is prepared in the same way as we have described for
depositing in copper moulds. When the deposit is made suffi-
ciently thick, the copper mould is peeled off and the two halves of
the figure soldered together. The copper moulds which are de-
posited upon the wax models taken in the elastic moulding are
often treated in the same manner; but more generally these moulds
are used for depositing silver or gold into them, to obtain fac-
similes of the object in these metals, in which case the copper
moulds are dissolved off by acids, as will be described in a subse-
quent section.
FIGURES COVERED WITH COPPER. — When plaster busts or figures
are wanted in copper, the most usual way is to prepare the figure
with wax as described, and to coat it over with a thin deposit of
copper, letting the copper remain. Some operators, when it can
be done, remove the plaster and wash over the inside with an alloy
of tin and lead melted. In this case the copper must previously be
cleaned by washing first in a solution of potash, and then with
chloride of zinc. The latter mode will cause the alloy to adhere
to the copper and give it strength. In either of these cases the
deposit must not be very thick, or it will throw the figures out
of proportion, such as the features of a bust, etc. Any slight
roughness of deposit may be easily smoothed down by means of
fine emery.
THE PREPARATION OF NON-METALLIC MOULDS TO RECEIVE
DEPOSIT. — Having detailed what we have found best for obtaining
moulds of objects for the purpose of electrotyping, we proceed to
the manner of obtaining a deposit upon these moulds. Were any
35
546 THE PRACTICAL METAL-WORKER's ASSISTANT.
of the plaster or wax moulds attached to the zinc and immersed in
the copper solution in the same manner as described with the
penny-piece (page 534), no deposit would be obtained, because
neither the plaster nor the wax is a conductor of electricity. Some
substance must now be applied to the surface in order to give it
conducting power. There are several ways of communicating this
property, but the best and most simple for the articles under con-
sideration is to apply common black lead (already referred to) in
the following manner : — A copper wire is put round the edge of
the medal, or, if wax moulds are used, a thin slip of copper may
be inserted into the edge of the mould — or, being slightly heated
and laid upon the back, the two will adhere. A fine brush is now
taken (we have found a small hat-brush very suitable) and dipped
into fine black lead, and brushed over the surface of the medal.
The brushing is to be continued until all the face round to the wire
upon the edge, or slip of copper forming connection, has a com-
plete metallic lustre. A bright polish is necessary to the obtain-
ing a quick and good deposit.
In brushing on the black lead, care should be taken not to allow
any to go upon the back or beyond the copper connection, or the
deposit will follow it, and so cause a loss of copper, and make the
mould more difficult to separate from the deposit ; being, as it
were, incased. If the electrotypist takes the labor himself of filing
off all the superfluous copper from the edge of his deposited medal,
it will do more than any written precautions to teach the necessity
of preventing as much as possible the deposit going further than
is necessary. When the face of the mould is properly black-
leaded, the copper wire connected with it is attached to the zinc
plate in the porous cell, and the mould immersed in the copper
solution ; the deposit will immediately begin upon the copper con-
nection, and will soon spread over every part, covering the black-
lead polish with less or more facility according to the state of the
solutions and other circumstances to be afterwards noticed. When
the deposit is considered sufficiently thick for removing — which,
in ordinary circumstances, will require from two to three days —
the medal is taken out of the solution, and washed in cold water,
and the connection is taken off. If the deposit has not gone far
over the edge of the mould, the two may be separated by a gentle
pull ; if otherwise, the superfluous deposit must be eased off) and
if eare be taken the wax may be fit to use over again : but when
the mould is plaster of Paris, however well it may be saturated
with wax, it is seldom in a condition to use again. If the plaster
mould be large and thick, it is advisable to coat the back with wax
or tallow, which is done by brushing it over with either substance
in a melted state : the mould being cold will not absorb the wax
or tallow : hence it may be recovered again., The sulphate of
copper possesses so penetrating a quality that if the slightest im-
perfection occurs in the saturation of the mould by wax, the solu
Lion will penetrate through it, and the copper will be deposited
ELECTROTYPE PROCESSES. 547
upon the face of the object adhering to th« plaster, giving to the
metal a rough, matted appearance, and seriously injuring it.
USING METAL MOULDS. — The mould in fusible alloy does not
require to be black-leaded, but the back and edge must be pro-
tected by a coating of wax or other non-conducting mate-rial ; it
may be connected in the same way as the penny-piece (page 531)
by putting a wire round its edge previous to laying on the non-
conducting substance, such as tallow or wax, which should also
cover the wire. Or a slip of copper, or wire, may be laid upon
the back and fastened by a drop or two of sealing-wax ; the back
is then coated : but care must be taken that the wax do not get
between the connection and the medal which will prevent deposit.
The deposit on this mould goes on instantaneously, the same as
over the penny-piece. When sufficiently thick, it may be taken
off in the same manner as from the wax mould, the surface having
been prepared by turpentine (page 534) to prevent adherence.
These moulds may be used several times, if care be taken not to
heat them, as they easily melt.
The medals obtained from metallic moulds prepared with the
turpentine solution have a bright surface, which is not liable to
change easily, but if the mould has been prepared with oil or com-
posed of wax or plaster, the metal will either be dark, or will very
easily tarnish. The means of preserving them, either by bronzing
or plating with other metals, will be detailed in a subsequent section.
PRECAUTIONS ON PUTTING THE MOULDS INTO A SOLUTION. — In
putting moulds into the copper solution, the operator is often an
noyed by small globules of air adhering to the surface, which
either prevent the deposit taking place upon these parts, or, when
they are very minute, permit the deposit to grow over them —
causing small hollows in the mould, which give a very ugly ap-
pearance to the face of the medal. To obviate this, give the mould,
when newly put into the solution, two or three shakes, or give the
wire attached to it, while the mould is in the solution, a smart tap
with a key or knife, or any thing convenient; but the most cer-
tain means we have tried, is to moisten the surface with alcohol
just previous to putting it into the copper solution. A little prac-
tice in these manipulations will soon enable the student to avoiu
these annoyances.
DEPOSITION ON LARGE OBJECTS. — When busts or figures,
whether of wax or plaster of Paris, are to be coated with copper,
with no other conducting surface than black lead, it is attended
with considerable difficulty to the inexperienced electrotypist. The
deposit grows over all the prominent parts, leaving hollow places,
such as armpits, neck, etc., without any deposit ; and when once
missed, it requires considerable management to get these parts
coated, as the coated parts give a sufficient passage for the current
of electricity. It is recommended by some electrotypists to take
out the bust, and coat the parts deposited upon with wax, to pre-
vent any further deposit on them ; but this practice is not good,
548 THE PRACTICAL METAL-WORKER'S ASSISTANT.
especially with plaster of Paris, for an electrotype ought never to
be taken out till finished. Sometimes the resistance of the hollow
parts is occasioned by the solution becoming exhausted from its
position in regard to the positive pole. In this case a change of
position effects a remedy. It may be remarked that when a bust
or any large surface having hollow parts upon it, is to be electro-
typed, as many copper connections as possible ought to be made
between these parts and the zinc of the battery. Let the connec-
tions with the hollow parts be made with the finest wire which can
be had, and let the zinc plate in the cell have a large surface com-
pared to the surface of the figure, and the battery be of considera-
ble intensity ; if attention is paid to these conditions, the most in-
tricate figures and busts may be covered over in a few hours. Care
has to be observed in taking off the connections from the deposit,
or the operator may tear off a portion of the deposit : if the wires
used are fine, they should be cut off close to the deposited surface.
To MAKE BUSTS AND FIGURES. — Busts and figures, and other
complicated works of art, which cannot be perfectly coated with
black lead, may be covered by a film of silver or gold, which
serves as a conducting medium to the copper. This is effected by
a solution of phosphorus in sulphuret of carbon. The operation
being patented, we will take advantage of the description given of
it in the specification. " The solution of phosphorus is prepared
by adding to each pound of that substance 15 Ibs. of the bisul-
phuret or other sulphuret of carbon, and then thoroughly agitating
the mixture; this solution is applicable to various uses, and
amongst others, to obtaining deposits of metal upon non-metallic
substances, either by combining it with the substances on which it
is to be deposited, as in the case of wax, or by coating the surface
thereof. Any of the known preparations of wax, may be treated
in this way, but the one preferred is composed of from 6 to 8
ounces of the solution : 5 Ibs. of wax, and 5 Ibs. of deer's fat,
melted together at a low heat, on account of the inflammable na-
ture of the phosphorus. The article formed by this composition
is acted upon by a solution of silver or gold in the manner here-
inafter described with respect to articles which have been coated
with the solution."*
COATING OF FLOWERS, ETC. — " If the solution is to be applied
to the surface of the article, an addition is made to it of one pound
of wax or tallow, one pint of spirits of turpentine, and two ounces
of India rubber, dissolved with one pound of asphalt, in bisul-
phuret of carbon, for every pound of phosphorus contained in
the solution. The wax and tallow being first melted, the solution
of India rubber and asphalt is stirred in ; then the turpentine, and
after that the solution of phosphorus is added. The solution pre-
pared in this manner is applied to the surfaces of non-metallic
substances, such as wood, flowers, etc., by immersion or brushing ;
* Repertory of Patent Inventions, 1844.
ELECTROTYPE PROCESSES. 549
the article is then immersed in a dilute solution of nitrate of silver,
or chloride of gold ; in a few minutes the surface is covered with
a fine film of metal, sufficient to insure a deposit of any required
thickness on the article being connected with any of the electrical
apparatus at present employed for coating articles with metal. The
solution intended to be used is prepared by dissolving four ounces
of silver in nitric acid, and afterwards diluting the same with
twelve gallons of water; the gold solution is formed by dissolving
one ounce of gold in nitro-muriatic acid, and then diluting it with
ten gallons of water."
We have frequently repeated the operations described by this
patentee with entire satisfaction, and were enabled to cover every
variety of surface with great facility.
The solutions of silver and gold, prepared as above, will last for
a long time, and do a great many articles. When it is convenient
it is best to use both solutions. The connecting wire should first
be attached to the article to be coated, before being dipped into
the phosphorus solution, but connected at such parts as will not
hurt the appearance of the object by leaving a mark when it is
taken off. Care should be taken not to touch the article with the
hands after it is dipped into the solution. The object supported
by the connections is immersed in the phosphorus solution, where
it remains for two or three minutes. When taken out it is dipped
into the silver solution, and as soon as the surface becomes black,
having the appearance of a piece of black china, it is to be dipped
several times in distilled water, and then immersed in the solution
of protochloride of gold about three minutes : the surface takes a
bronze tinge by the reduction of the gold. It is next washed in
distilled water by merely dipping, not by throwing water upon it.
The wire connection is now attached to the zinc of the battery,
and then the article put into the copper solution, and in a few
minutes the article is coated over with a deposit of copper. A
thin copper surface may thus be given to small busts or figures
without sensibly distorting the features by want of proportion.
FIGURES FROM ELASTIC MOULDS. — When taking a wax cast
from the elastic mould, described in page 544, we prefer the phos-
phorized mixture. After taking out the mould it is only neces-
sary to make the connections, and pass it through the gold and
silver solutions, as described, and then to connect it with the
battery.
WTe may also mention that the principal object of making cop-
per moulds by this process, in the manufactory, is not to make fac-
similes in copper, but to make articles of solid silver or gold.
Copies of highly wrought work, either chased or engraved, or of
articles, duplicates of which cannot be obtained, or of which the
workmanship is costly, may by this means be made in solid silver
or gold, at little more expense than the cost of the metal. Having
obtained the copper mould, silver is deposited in it to any thick-
ness, and the copper dissolved off. However, an extensive trade
550 THE PRACTICAL METAL-WORKER^ ASSISTANT.
is now being carried on in figures and other works of art deposited
in copper and then bronzed, which gives them an appearance often
not much inferior to that of antique works of the highest art.
ELECTROTYPES FROM DAGUERREOTYPES. — What may be justly
termed the perfection of electrotyping, is the production of elec-
trotypes from daguerreotypes. The daguerreotype picture being
taken, a small portion of the back is cleaned with sand-paper, taking
care not to allow any thing to touch the face ; a little fine solder is
placed on this part; a piece of flattened wire, also cleaned, is
placed upon the solder, the whole moistened with dilute muriatic
acid, or chloride of zinc. The wire is now held over the gas or a
lamp about half an inch from the plate ; the heat is transmitted
through the wire to the solder, which melts, and the wire is sold-
ered to the type ; the back is then protected by wax, and the
daguerreotype is now put into the copper solution in the same man-
ner as a medal ; the deposit proceeds rapidly, and when sufficiently
thick the two easily separate, and an impression of the picture is
obtained from the daguerreotype with an expression softer and
finer than the original ; several electrotypes may, with care, be
taken from one picture. The electrotype may now be passed
through a weak solution of cyanide of gold and potassium, in con-
nection with a small battery, and thus a beautiful golden tint be
given to the picture, which serves to protect it from the action of
the atmosphere; but they should also be protected by a glass,
which may be fixed on in the manner pointed out in another sec-
tion. The most successful operators that we have known in this
and every other department of electrotyping are Dr. Thomas
Paterson, of Glasgow, and Mr. Bawtree, of London.
DEPOSITING BY SEPARATE BATTERY. — Having described, so far
as we know them, the best and most simple means of obtaining
moulds, and their preparation for receiving the deposit of the
metal, we return again to the management of solutions and bat-
teries, and the application to other metals besides copper.
Although in our account of the porous or single cell system
(page 533) we have recommended it as the best and most economi-
cal for electrotyping, still many eminent electro-metallurgists prefer
using the battery system ; and indeed there are solutions of copper
and of other metals to which the porous cell system cannot be ap-
plied, from the nature of the solution and the necessity of intensity
to decompose them.
While depositing upon a mould by the single cell, let the wire
which connects them be cut in the middle, and a mould be attached
to the end of the portion remaining upon the zinc plate, and a
small plate of copper to the end of the wire remaining upon the
mould in the copper solution, and let these two be put into a second
vessel containing a solution of sulphate of copper. The action
between the zinc and medal in the double or first cell will go on
as before — namely, the electricity passing through the porous cell
imd the solution to the medal; but on returning to the zinc it must
ELECTROTYPE PROCESSES.
551
pass through the copper solution, which is in the second vessel,
between the mould and copper plate, where it produces the same
effects as in the first cell. The sulphuric acid is liberated at the
copper plate and dissolves it, and the copper is deposited upon the
mould, so that the solution in this cell is maintained at one strength ;
hence there is no necessity for hanging crystals of sulphate of
copper in this solution.
It will be observed that the electricity having to pass through a
second solution, is made to perform double duty, and must conse-
quently be much more economical. We found the results to be
these : A single cell, with a mould, was placed two inches from the
porous cell, and of the same size as the zinc plate ; and another,
similarly arranged, but connected with a metal mould and copper
plate of similar size to the zinc and copper, was placed one inch
apart in the copper solution of second cell. The mould in the
single cell had gained 100 grains, and the zinc plate lost 108
grains. The mould in the battery cell of the other arrangement
had only deposited upon it
30 grains— the zinc plate Fig. 573.
had lost 35 grains ; but the
mould in the second or de-
composition cell had also
deposited upon it 30 grains,
making in all 60 grains de-
posited for 35 zinc dissolved,
but taking nearly double the
time. These arrangements,
as we have before observed,
are simply a modification
of a single pair of Darnell's battery connected with a decompo-
sition cell, the advan-
tages of which are not Fig. 574.
applicable to any other
battery, as in no other
battery does deposition
take place within the
battery cells : indeed this
method of using a com-
pound depositing appa-
ratus is very seldom em-
ployed. Batteries of a
different form, as Smee's
are generally adopted.
Figure 573 represents a
Smee's battery, connected with a medal and copper plate in a sepa-
rate or decomposition cell ; and Fig. 574 is a large decomposition
trough for doing several medals at one time. Of course any bai-
tery may be attached to these medals and plate by the brass con-
nections seen on the end of the trough. Bear in remembrance
552
THfi PRACTICAL METAL-WORKER'S ASSISTANT.
that the zinc of the battery is connected with the m trials, and
the copper or platinized silver with the copper in the decompo-
sition cell.
SIZE OF THE ELECTRODES. — "When a separate battery is used for
the purpose of depositing in a decomposition cell, there are several
conditions which are well to be observed, as they influence the
amount and character of the deposit. The first is the size of the
electrodes or medals, in relation to the zinc in the battery. The
results we have obtained may be expressed in general terms.
When the deposit upon electrodes of the same size as the zinc
plates in a Wollaston's battery equals 100, that upon electrodes one
half the size of the zinc plates in the battery will be equal to 57,
and upon electrodes double the size of the zincs of the battery 190;
but this last condition is affected by the intensity of the arrange-
ment.
KELATIVE POWER OF BATTERIES. — The following experiments,
made with electrodes double the size of the zinc plates of the bat-
teries, all at equal distances (1 inch apart), will show the relative
power of the batteries. The time in action was one hour each :
only one pair of plates constituted the battery.
Grove's battery deposited . . 104 grains.
Single cell 62 "
Daniell's 33 "
Smee's 22 "
Wollaston's 18 "
CONSTANCY OF BATTERIES. — But the first hour of the action of
most batteries differs from an hour afterwards, so that one kind of
battery may be most useful for a short time, and another sort if
the action is to be continued for a length of time. The following
table will illustrate this remark, the condition being the same as in
last experiment, or the last experiments being continued, and the
results taken every hour for seven successive hours :
1
2
3
4
5
6
7
hour.
hours.
hours.
hours.
hours.
hours.
hours.
Total.
Grove's battery .
Single cell . . .
104
62
86
57
66
54
60
46
54
39
49
29
45
24
464 grs.
311 "
Daniell's . . .
33
35
34
32
32
30
31
227 "
Smee's ....
22
16
14
11
12
11
10
96 "
Wollaston's . .
18
14
15
12
11
10
10
90 "
To make this comparision more practical, larger plates were used
for the battery, and proportionately larger electrodes, and the bat-
tery kept in operation until one pound of copper was deposited,
ELECTROTYPE PROCESSES. 553
v
renewing -the acid, and brushing the zincs every 24 hours. The
time taken to effect this was:
Grove's Battery . .. . . . 19 J hours.
Single cell 45
. Daniell's* 49
Smee's 147
Wollaston's .151
COMPARATIVE PRODUCE OF BATTERIES. — The expense of the
materials used in these experiments was as follows (of course the
materials will differ in cost both at different times and in different
localities, and more common materials may be used) :
By the process with Grove's battery, one pound of deposited,
copper costs
1 Ib. Copper, from positive electrodes ... 25 cts.
1J Ib. Amalgamated zinc 21 "
1J Ib. Nitric acid 19 "
Sulphuric acid 02 "
67 cts.
Add time, say one cent per hour, for comparison . . 20 "
87 cts.
By single cell apparatus, one pound of deposited copper costs
1 Ib. Sulphuric acid 04 cts.
ly^ Ib. Amalgamated zinc 17 "
4 Ib. Sulphate of copper ........ 37 "
58 cts.
Time, at one cent per hour 45 "
$1.03
By Daniell's battery, one pound of deposited copper costs
1 fg Ib. Amalgamated zinc 19 cts.
4 Ib. Sulphate of copper 37 "
1 Ib. Copper from electrode 25 "
Sulphuric acid 02 "
83 cts.
Time, at one cent per hour 49 "
$1.32
* The Daniell's battery used in this experiment had flat plates, not circular,
i describe i at page 523.
554: THE PRACTICAL METAL-WORKER'S ASSISTANT.
By Smee'h battery, one pound of deposited copper costs
1J Ib. Amalgamated zinc 21 cts.
3 Ib. Sulphuric acid 12 "
1 Ib. Copper from electrode* 25 "
58 cts.
Time, at one cent per hour $1.47
$2.05
By Wollaston's battery, one pound of deposited copper costs
1 Ib. Copper from electrode 25 cts.
1 -,2ff Ib. Amalgamated zinc 19 " •
3 Ib. Sulphuric acid 12 "
55 cts.
Time, at one cent per hour $1.51
$2.06
By thus adding the time, at a given rate, it serves to illustrate
what we have before stated respecting the necessity of placing the
value of time against the cost of materials. In manufactories,
where time has to be paid for, it may be cheapest to use the bat-
tery with the most costly materials ; but where time is of no con-
sideration, or, as is often the case, if, while the operations are going
on, the workmen are employed in other necessary labor, a cheaper
apparatus will answer: but the student or manufacturer will, by the
above general results, be enabled to choose the process most suit-
able for his purposes. It must be borne in mind that an allowance
has to be made on the first, second, and third, for wear and tear of
the porous vessels, not included in the above estimate. Although
the results of these experiments give, exclusive of time, the cost of
one pound of electrotyped copper — thus
Grove's battery . . . 67 cts.
Single cell 58 "
Daniell's 83 «
Smee's 58 "
Wollaston's 55 "
still we know from long experience in the use of single cell, Smee's,
and Wollaston's batteries, for manufacturing purposes, that the
price of the pound of copper deposited may be more correctly
stated at 62 cents — there being always loss in making the purest
article (the copper) from impure materials, as the sulphate of cop-
per, or the ordinary copper of commerce which is used as elec-
trodes.
Mr. Smee. in his "Advice to capitalists who propose entering
ELECTROTYPE PROCESSES. 555
upoii the business of electro-metallurgy," gives a table of expenses
incurred by the use of different batteries. But his rules are based
too exclusively upon theoretical considerations, and without that
regard for practical conditions which are so important to the manu-
facturer. Mr. Smee recommends for use what he calls " an odds-
and-ends battery/' composed of odd scraps of zinc put into acid,
having in the same vessel a piece of copper or platinized silver and
a wire placed in contact with them which forms the electrode.
This battery may be convenient for the amateur electrotypist, as it
enables him to use up all his waste zinc. Eaw zinc, or spelter, Mr.
Smee says, may also be used in this way, constituting the cheapest
of all batteries for manufacturing purposes. The data of his cal-
culations are as follows : — The copper sheet forming the positive
electrode is quoted at 25 cents per Ib. ; wrought zinc, 14 cents per
Ib. ; raw zinc at a little more than half the price of wrought zinc,
which we will call 8 cents per Ib., although he rates it at 10 cents.
Iron is given at from 2 to 4 cents per Ib. The equivalent weight
of copper is given at 32, of zinc at 32, and of iron at 28 ; that is
to say, 32 parts (say ounces) of zinc dissolved in a battery will, or
should deposit 32 ounces of copper; and if iron be used, 28 ounces
of iron should deposit 32 ounces of copper. Hence, in the plain
language of a manufacturer, we should say that, with an odds-and-
ends battery and raw zinc, there would be, for every pound of cop-
per deposited,
16 oz. of zinc used .... 08 cts.
16 oz. of copper dissolved . . 25 "
33 cts.
And when iron is used, the expense of depositing 1 Ib of copper
would be,
16 oz. of iron, say .... 01 cts.
16 oz. of copper 25 "
29 cts.
Notwithstanding these results, Mr. Smee proves, by several frac-
tional formulae and an algebraic equation, that the cost of deposit •
ing a pound of copper is
Bv, iron 37 cts.
By odds-and-ends battery . . 25 " *
62 cts.
To this it may be replied by the manufacturer, that, in the first
place, raw zinc or spelter used in the way described for an odds-and-
ends battery would lose two or three times the quantity that is
stated for every equivalent of copper ; and secondly, that this form
* Smee's Elements of Electro-metallurgy, 3d edition, p. 112.
556 THE PRACTICAL METAL-WOBKElVs ASSISTANT.
of battery is altogether unsuitable for manufacturing purposes,
even when amalgamated scrap zincs are used ; and, as regards the
calculation, it is not easy to see that, while a pound of copper, dis-
solved 'from the positive electrode, originally costs 25 cents, it
could, notwithstanding, be deposited by the destruction of 1 Ib. of
zinc, not including acid, etc., at the expense of only 25 cents. It
ought always to be remembered, that, for manufacturing purposes,
the surface upon which the metal is to be deposited in general
amounts to several square feet. The article may be, for example, a
large ornamental vase, having four square feet of surface. An
odds-and-ends battery, or an iron single pair battery would be too
weak. To deposit, with a separate battery, upon a surface such as that
of the vase, it requires two or three pairs of plates to give what we
may call economical power.
KECOVERY OF MERCURY FROM WASTE ZINC. — The general
practice of manufacturers, when the scraps of zinc become small,
is either to treat them as referred to at page 512, to distil the mer-
cury from the zinc, or to sell the scraps to parties who do distil
them. This is done by putting the scraps into an iron retort, sub-
jecting it to a red heat, and allowing the beak of the retort to pass
into a condenser, which has a tube dipping into water. The mer-
cury distils over, and condenses in the water. The zinc left in
the retort is found to be so impure as not to be fit to melt and roll
again, but it may be used in the composition »of common brass.
Mr. De la Rue, in a communication to the Chemical Society,* gives
the results of several analytical experiments upon scrap zinc. Be-
fore distillation the scraps usually give the following results in 100
parts :
Zinc 67-3
Mercury .... 4*3
Dross and loss . . 28*4
100-0
The composition of the zinc left after distillation is given as —
Zinc . . . . .90'
Iron 2'56
Lead 6-
Copper . . . . 1*44
100-00
COMPOUND CELL PROCESS. — Another method of economizing
power was proposed in what is termed the compound cell system,
by which it was said that the electricity passing through a series
of cells would be able to produce the same quantity of work in
every cell with no more cost. This plan may be stated thus :
A is a Smee's battery; the wire z is conducting the electricity to
* Memoirs and Proceedings of the Chemical Society, vol. ii. page ->93.
ELECTROTYPE PROCESSES.
557
the compound trough which is composed of a series of water-tight
cells, as a a, and is connected with a piece of- copper c, forming a
positive electrode ; in the same cell, and facing this electrode, is &
medal, connected by a copper wire to a piece of copper placed in
the second cell, opposite which is another medal connected in the
Fig. 575.
a- a
^T^^T^Tr^VT^A
same manner with another piece of copper, and so on through the
series, which terminates with a medal attached to the wire of the
battery. The electricity from the battery passes through all these
cells, and reduces its equivalent in each cell. Thus the reduction
of 32 grains of zinc in the battery would deposit 32 grains of
copper multiplied by 6 times, or as many times as there are cells.
This is correct in principle, and at first sight seems to be exceed-
ingly economical ; but it is not so, for every cell adds so much to
the resistance of the current, that intensity batteries must be used ;
so that, supposing we have a compound cell of six divisions, in
which are placed six separate medals, it would require a battery
of six pairs of plates to give intensity sufficient to overcome the
resistance, and the same number of medals could be made of the
same weight by six separate zincs, and in less than half the time
they could be made by this arrangement, and with a less destruc-
tion of zinc. For large operations, where the articles receiving
the deposits and the electrode are necessarily a good way apart,
the process is altogether impracticable in a commercial point of
view. This is one of the remarkable instances where theoretical
possibility and commercial economy are at variance.
EFFECTS OF EESISTANCE. — At page 551 we mentioned, that if a
single cell deposits 100 grains in a given time, and it be converted
into a battery having the two electrodes in a solution of sulphate
of copper, there will only be deposited in the same time 30 grains.
This is caused by the extra resistance which the solution between
the two electrodes, in the decomposition cell, offers to the passage
of the electricity, the amount of which corresponds to the amount
deposited — the latter depending upon the former.
If we take two small plates of copper and zinc amalgamated,
and place them in dilute sulphuric acid, in contact, but not so close
as to prevent the gas evolved from the copper plate to escape, and
allow them to remain until there have boen dissolved from the ziue
558
THE PRACTICAL METAL-WORKER^ ASSISTANT.
Fig. 576.
100 grains, and we call this the measure of the maximum amount
of electricity which Jhat surface of zinc and copper can give out
in the time taken to dissolve the 100 grains: then, if the two
metals in the acid be separated one inch, being connected by a
wire or slip of copper above the liquid, and kept in action the
same length of time as the former, there will be dissolved from the
zinc only about 56 grains. If the wire in connection with the zinc
and copper be extended and cut in the middle, and have a piece
of copper attached to each of the same size as the zinc plate in
acid, and these be placed in another vessel containing a solution
of sulphate of copper (as Fig. 544), and put an inch apart, and
the whole kept in action the same length of time as before, it will
be found in this case that only 10 grains of zinc are dissolved.
From these experiments we see that the resistance of the one
inch of acid between the zinc and copper in the battery, and the
one inch of solution of sulphate of copper in the second or de-
composition cell, is 90 or nine-tenths — only yielding one-tenth of
the electricity which the zinc and copper are capable of giving.
INTENSITY. — If we now take another zinc and copper plate of
the same size as the former, and arrange them in the acid solution,
and connect them with the copper plates in the decomposition cell,
as shown in Fig. 544, and keep
them in action the same length
of time as in the former experi-
ments, there will be dissolved
from the zinc about 19 grains,
and deposited upon the copper
plate attached to the zinc in the
decomposition cell 18 grains of
copper.
If three zincs and coppers be
arranged as described and placed in the acid, there will be dis-
solved from the zinc plate 26 grains, and deposited upon the copper
25 grains. If six pairs zinc and copper be arranged as above and
placed in acid, there will be deposited 36 grains of copper, which
we will also take as the measure of what is dissolved from the zinc ;
and if nine pairs of zinc and copper be used, there will be de-
posited 43 grains, and so on until the quantity dissolved from each
zinc, or deposited on the copper plate be 100, equal to that ob-
tained by the close contact of the zinc and copper in acid, which
will require upwards of 30 pairs of zinc and copper. It must be
borne in mind that the same quantity of zinc will be dissolved
from every plate in the arrangement. Thus, in nine pairs where
43 grains were deposited, there would be dissolved from every zinc
in the battery 43 grains.
It will now be apparent that the use of sevejal pairs in the bat-
tery is to overcome resistance, by which quantity is gained at the
same time up to a given point; but quantity gained by this means
is expensive. The 10 grains deposited by the single pair of
ELECTROTYPE PROCESSES.
559
zinc and copper only required 10 grains of zinc, but the 43
grains by the nine pairs would require 405 grains of zinc to be
dissolved.
RELATIVE INTENSITY OF BATTERIES. — Different batteries have
different degrees of power to overcome resistance — greater in-
tensity. The following experiments will illustrate this : A single
pair of a Wollaston's, Smee's, and Grove's batteries were fitted up
as nearly equal in circumstances as the different arrangements
would allow — each exposing the same surface of zinc, and con-
nected with electrodes placed in a solution of sulphate of copper,
first 1 inch, then 2 inches, 3 inches, and 4 inches apart — half an
hour in each. They were then reversed, beginning with the elec-
trodes at 4 inches and coming to 1 inch. These experiments were
repeated several times, and a mean of the whole taken. The re-
sults were :
Deposited —
Electrodes 1 inch ,
2 inches
3 inches
4 inches
Wollastou. Smee.
. o'o grains
. 6-6 "
. 4-7 "
. 3-0 "
12-0
6-8
6-0
4-6
Grove,
31-0
26-0
17-0
14-0
From this it will be seen that Wollaston's stands lowest in in-
tensity, which is more apparent as the distance of the electrodes is
increased. Smee's is one-third more than Wollaston's at 1 inch,
and one-half more at 4 inches ; while Grove's is three and a-half
more than Wollaston's, and two and a-half more than Smee's at
1 inch, but four and a-half more than Wollaston's and three
more than Smee's at 4 inches. If we take the mean of these
results as a comparison of batteries, their value will stand as
under:
One of Grove's equal to three of Smee's,
and to three and three-fourths of Wollaston's.
The following table gives the results of different batteries, ar-
ranged in series, kept in action the same length of time, namely,
one hour. The battery plates were very small, the electrodes
twice the size of the battery plates :
One
Pair.
Two
Pairs.
Four
Pairs.
Six
Pairs.
Nine
Pairs.
Grove's
55
7?,
93
97
98
Daniell's
15
35
60
77
86
Smee's
11
19
29
41
58
Wollaston's
8
15
24
33
48
. 0 .
560 THE PRACTICAL METAL-WORKER'S ASSISTANT.
This table gives results approaching to and in principle the same
as the others : it will be observed that one pair of Grove's is equal
to nine pairs of either Wollaston's or Smee's. It is also worthy of
remark, that Grove's increases slowly in quantity above four pairs,
the intensity being sufficient at four pairs to overcome the resist-
ance offered to the current of electricity. For ordinary electro-
typing, intensity arrangements are unnecessary, except where the
article upon which the deposit is being made is of such a character
as will not allow the positive electrode to be brought close to it, or
when there are deep cut objects, or any circumstance that increases
distance and necessitates power to overcome resistance.
MODE OF SUSPENDING OBJECTS FOR COATING. — In beginning to
operate in the art of electrotyping, the student often pauses, and asks
the question, What is the best position in which a medal should be
hung in the solution? Convenience has brought into general prac-
tice the suspending of it perpendicularly in the solution, having the
positive electrode or pole facing it in a parallel
577- direction; but to this method there are somo
objections. If, for instance, the porous diaph-
ragm, or single-cell system be used, for obtain-
ing the medals, it is found that upon the lower
portion of the medal the deposition is much
thicker than upon the upper portion. Indeed,
when even ordinary attention is not paid, the
lower part becomes not only thicker, but stud-
ded over with round nodules of copper, or with lines composed of
these nodules, while the upper part remains thin, and is covered over
with what is termed the sandy deposit copper, in dark brown grains,
capable of being rubbed off with the slightest friction. No doubt
this is in a great measure prevented by agitating the solution ; but
it is inconvenient, and requires constant attention.
If a separate battery is used, and the deposition of the medal is
effected in a separate vessel, by having a copper positive electrode,
the same inconvenience takes place to a greater or less extent,
according to the distance at which the two poles are placed. These
inconveniences are known to all electrotypists, and the cause is
ascribed to the different densities of the solution. The reason why
the solution becomes of different densities is easily understood in
the single cell process, there being no copper pole to maintain the
strength of the sohition; as it becomes exhausted of copper by the
deposition, the lighter portion floats on the top, and the heavier
portion remains below ; and although crystals of sulphate of cop-
per be suspended in the solution, as they dissolve they sink by their
gravity, and cause a flow upon the lower portion of the medal, and
consequently a much more powerful deposit. But why the same
should take place with a separate battery, where there is a posi-
tive electrode of copper being dissolved, just in proportion to the
copper extracted from the solution by the medals, was for a long
time riot known.
ELECTROTYPE PROCESSES. 561
NON-TRANSFER OF ELEMENTS. — Tn a paper read upon this sub-
ject before the Eoyal Society by the late Professor Daniell and
Professor Miller, they gave, as the results of their investiga-
tions, that certain metals are transferred by the electric current in
small proportion, differing in different metals.* About the same
time the author had observed, when operating upon the large scale,
results which led him to the conclusion, that no metal is trans-
ferred in any quantity by the electric current, nor any element
taking the position of the metal in an electrotype, but that the
acid element was always transferred equivalent to the electricity
passing. It was thus shown that during the deposition of metal,
say copper, in electrotyping, the acid, when exhausted of the cop-
per at the surface of the medal, is transferred to the positive-pole,
and dissolves a portion of copper ; but this portion is not transferred
by the electric current to the medal : hence it will be observed,
that the solution next the medal will become exhausted of cop-
per, and will consequently rise to the surface from its greater
lightness. There is no doubt a flow of stronger solution in a hori-
zontal direction from the positive pole to the medal, caused by the
lighter portion ascending; but this does not mend the evil: the
light portion is increasing on the surface, and the whole solution
soon becomes of different densities from the surface to the bottom
of the medal ; and this constant current of the
solution flowing up the surface upon which the Flg* 578*
elect rotypist is depositing, causes the lines that
are observed in deposits under certain circum-
stances, and which are sometimes very annoy-
ing. If a small hollow be in the mould, or
even if a small portion of a plain surface resist,
the metal will accumulate round the edge of
the resisting portion, giving the deposit an ap-
pearance as if made in a flowing stream, like a
stone standing up in a current of water. The black point in the
centre represents the resisting spot around which the deposit will
thicken, causing a ridge of metal to radiate to a point immediately
above the resisting portion. These disappointments are much
more annoying in solutions of gold and silver than in sulphate of
copper, as will be noticed when we come to treat of plating and
gilding. A point of grease or dirt, or small hole not cleaned out,
hardly visible to the naked eye, will give a very prominent effect
upon the plain polished surface of a piece of metal.
From these observations, the reader will now be able to answer
the question — what is the best position to place a medal in the
solution ? To make it still more apparent, take a glass jar, filled
with a solution of sulphate of copper; place a piece of copper
upon the bottom of the jar, and suspend the medal at the top,
* Philosophical Transactions, Parti, for 1844; and Memoirs and Proceedings
of the Chemical Society, Vol. iii. page 53.
36
562 THE PRACTICAL METAL-WORKER'ri ASSISTANT.
having their two faces parallel ; connect them with a battery ; in
a short time the solution round the medal becomes exhausted, and
even colorless, the medal covered with a dirty brown powder, and
no further deposit will take place. But reverse the case ; place
the medal at the bottom, and the copper positive electrode at the
top ; the deposition goes on constant and smooth ; the solution is
maintained in the same condition as it was at the first, there being
a constant transfer; the acid is transferred by the current from the
medal to the copper pole : the sulphate of copper formed descends
by its gravity to the medal. There are, no doubt, a few slight
objections to placing the medal under the positive electrode — such
as the impurities in the copper getting disintegrated, and falling
upon the surface, but a piece of cloth wrapped round the pole pre-
vents this. However, when a fine surface is wanted, care ought
always to be taken to have clean solutions filtered, and kept cov-
ered from dust ; and when the single cell is used, the crystals of
sulphate of copper should be suspended in a fine linen bag, or the
shelf holding them be lined with linen.
EFFECTS OF DIFFERENCE IN THE DENSITY OF SOLUTION. — Al-
though in principle this is the best method, we believe that very
few practice it, because of the trouble attending the arrangement
oi the electrodes in this position. When the medals are small the
annoyances from unequal density are not so material, but if the
surface of the article which is being deposited be large — say eight
inches or upwards — the difference in the thickness of the lower
and upper portion of the medal is very great. When suspended
perpendicularly, they should be shifted several times, making the
upper portion the lower, besides occasionally stirring the solution,
or shaking the article. Indeed when convenient, the article re-
ceiving the deposit should be kept as much in motion as possible,
as it regulates the deposit, making it smoother and less brittle.
CRYSTALS OF COPPER ON ELECTRODES. — It will be found, when
working with a battery, that the sulphate of copper solution will
become stronger round the positive electrode, which is gradually
dissolved by the transferred acid. A frequent effect is, that the
electrode often gets coated over with crystals of sulphate of cop-
per, which adhere with great tenacity, and stop the electric action.
Under such circumstances, it is only necessary to clean the elec-
trode from the crystals and to add a little water to the solution,
which will prevent a recurrence of the crystals for a time. But
the stirring of the solution occasionally will do much to prevent
this crystallization.
ELECTROTYPE PROCESSES. 563
CHAPTER XXVII.
MISCELLANEOUS APPLICATIONS OF THE PROCESS OF COATING
WITH COPPER.
BESIDES the applications and processes which we have described
u tier the general term of electrotyping, there are various applica-
ti* ns of the process of depositing metals upon other substances,
wmch have been, and may be still more usefully applied. We
ma, 7, at a trifling cost, impart a coating of copper to cornices for
decorating buildings, to terra cotta, engravings on wood, etc., etc.
Cloth may also be easily covered, and made to assume the appear-
ance of a sheet of copper, having the lightness and pliability of
cloih. Lace has been covered with copper, and used for battery
plates, and has also been gilt and made into beautiful ornaments.
Table-covers with metallic ornaments richly gilt, and book-covers,
have all been tried with more or less success, although they have
Qot yet been profitably produced.
COPPERED CLOTH. — Ordinary cloth, covered with copper, was
prepared a few years ago in considerable quantities for the cover-
ing of roofs, wagons, etc. ; but the necessary price precluded its
use when competing with the ordinary materials for these pur-
poses, although it possesses many eminent qualities for some of
these uses — such as forming fire-proof covers to shelter wagons
from the sparks discharged by a locomotive. The choice of the
kind of cloth was another difficulty ; linen was too expensive, and
required a good coating of copper to make it water-tight ; the best
substance was a felted cotton with India-rubber, but after a few
months exposure the India-rubber in the cloth decomposed. The
operations of coating cloth with copper were the same as described
for the wax medals : the cloth was brushed over with a polish of
black lead, and then stretched upon a frame of wood having a
copper band round it, in which were placed small hooks or pins,
and the cloth attached to these. A vat, four feet deep and twelve
yards long, was made of brick and cement; this was divided
lengthwise by a wooden frame with panes the same as a window,
which were filled in with unglazed earthenware plates, cemented
by marine glue, and the whole made water-tight. Into one divi
sion of the vat were placed the dilute acid and sheets of zinc ; in
the other the solution of copper, in which was placed the cloth
upon the frame. The arrangement was so perfect that we have
often seen pieces of cloth, twelve yards long by one yard wide,
completely covered with copper in one hour. The result of many
trials was, that one pound weight of copper gave a perfect solid
covering to twenty superficial square feet of cloth.
A similar thickness is quite sufficient for other surfaces for mere
exposure to the atmosphere, such, as wood- work, cornices, etc., arid
664: THE PRACTICAL METAL-WORKER'S ASSISTANT.
may be produced at the same rate, about 2s. 6d. per pound of
copper.
Besides these applications, many others have been suggested
and tried with variable success. Some have probably been aban-
doned too soon, others have had both capital and talent applied,
and success is yet to come. We shall only name a few of these
applications.
CALICO PRINTERS' EOLLERS. — So early as 1841 active means
were tried to apply the electro-deposition of copper to the prepara-
tion of rollers for printing calicoes, both by depositing the copper
upon wax or other moulds, to make an entire roller of copper, or
to deposit a surface of copper on other metals, such as iron or
brass ; but none of them have yet succeeded. To make an entire
roller is much more expensive, without an equivalent advantage
over the ordinary method of casting, rolling and boring. To de-
posit a layer of copper on iron is attended with many practical
difficulties, both in protecting the iron from the acid solution for
so long a time as is required to deposit the proper thickness, and
in securing the adhesion of the two metals during the subsequent
operations. It requires a deposit of about a quarter of an inch in
thickness to allow for turning before engraving. There is then
the annealing to soften the copper, etc., which interferes with the
adhesion of the two metals, probably from their different rates of
expansion, and other causes. Similar objections may be made to
the coating of brass rollers with copper. Numerous and varied
have been the experiments made, but all without success ; never-
theless we have every confidence that means will be obtained for
producing rollers by the electro process.
ETCHING OF HOLLERS. — Another application of the process to
printers' rollers was to plate the surface of the roller with silver for
the purpose of etching. The engraving is then made through the
silver coating ; the roller is next passed through nitric acid, which
acts upon the exposed copper, the silver taking the place of var-
nish in ordinary etching : but practical difficulties have caused the
abandonment of this application also.
PRINTING. — The electro-metallurgical process has been applied to
many operations in ordinary printing. Mr. Warren de la Rue has
been eminently successful in many of these applications. It has also
been applied to plates for printing music, and for embossing soft
materials, such as leather. By depositing a sheet of copper upon
a skin of morocco leather, it may be used for imparting an im-
pression to other skins of leather, giving them the appearance of
fine morocco.
The printing of music has also been successfully done by elec-
trotyping the plate from a stereotype cast. The same may be done
from ordinary stereotype plates.
GLYPOGRAPHY. — A process which Mr. Palmer, the inventor,
named Glyphography, has been one of the most successful at-
tempts to apply the electrotype to the art of engraving. The
ELECTKOTYPE PKOCESSES. 565
principle of the invention consists in depositing copper in the
grooves or engravings made in a layer of some soft substance
spread on a sheet of copper, and covering the whole with a sheet
of electrotype copper. The counterpart of the engraving thus
produced is used for printing from in the same manner as letter-
press primers' types or woodcuts. It may therefore be called a
mode of stereotyping, with this difference, that it is made directly
from the drawing by the artist. The drawing, however, must be
made in a particular way, which, with the other necessary manipu-
lations, is thus given by Mr. Palmer : *
"A piece of ordinary copper plate, such as is used for engraving,
is stained black on one side, over which is spread a very thin layer
of white opaque composition, resembling white wax both in its
nature and appearance. This done, the plate is ready for use.
" In order to draw properly on these plates various sorts of
points are used (according to the directions here given), which re-
move, wherever they are passed, a portion of the white compo-
sition, whereby the blackened surface of the plate is exposed, form-
ing a striking contrast with the surrounding white ground, so that
the artist sees his effect at once.
11 The drawing, being thus completed, is put into the hands of
one who inspects it very carefully and minutely, to see that no part
of the work has been damaged or filled-in with dirt or dust ; from
thence it passes into a third person's hands, by whom it is brought
in contact with a substance having a chemical attraction or
affinity for the remaining portions of the composition thereon,
whereby they are heighted ad libitum. Thus, by a careful manipu-
lation, the lights of the drawing become thickened all over the
plate equally, and the main difficulty is at once overcome. A little
more however remains to be done. The depth of these non-print-
ing parts of the block must be in some degree proportionate to
their width, consequently the larger breadths of lights require to
be thickened on the plate to a much greater extent in order to pro-
duce this depth. This part of the process is purely mechanical
and easily accomplished.
" It is indispensably necessary that the printing surfaces of a
block prepared for the press should project in such relief from the
block itself as shall prevent the probability of the inking-roller
touching the interstices of the same whilst passing over them.
This is accomplished in wood engraving by cutting out these in-
tervening parts, which form the lights of the print, to a sufficient
depth ; but in glyphography the depth of these parts is formed by
the remaining portions of the white composition on the plate,
analogous to the thickness or height of which must be the depth
on the block, seeing that the latter is, in fact (to simplify the mat-
ter), a cast or reverse of the former. But if this composition were
* Glyphography, or engraved drawing, for printing at the typo press after
the inauner of woodcuts, 1844.
566 THE PRACTICAL METAL-WORKER'S ASSISTANT.
spread on the plate as thickly as required for this purpose, it
would be impossible for the artist to put either close, fine, or free
work thereon ; consequently the thinnest possible coating is put on
the plate previously to the drawing being made, and the required
thickness obtained ultimately as described.
" The plate thus prepared is again carefully inspected through a
powerful lens, and closely scrutinized to see that it is ready for the
next stage of the process, which is to place it in a trough and sub-
mit it to the action of a galvanic battery, by means of which copper
is deposited into the indentations thereof, and, continuing to fill
them up, it gradually spreads itself all over the surface of the com-
position until a sufficiently thick plate of copper is obtained, which
on being separated will be found to be a perfect cast of the draw-
ing which formed the clichee.
" Lastly, the metallic plate thus produced is soldered to another
piece of metal to strengthen it, and then mounted on a piece of
wood to bring it to the height of the printer's type. This com-
pletes the process, and the glyphographic block is now ready for
the press.
"It should however have been stated previously, that if any
parts of the block require to be lowered, it is done with the greatest
facility in the process of mounting."
This process has however not come into much use as a substi-
tute for wood engraving, in consequence of the impossibility of
finding a suitable varnish for the use of the artist or engraver. It
has, in fact, given way to another process, also embraced in Mr.
Palmer's patent, which is worked thus : A copper plate is etched
by the process commonly employed by engravers, the lines being
cut into the copper with a bold stroke. The lines are then bitten
deeper by nitric acid. The etching is made direct, not reversed, as
it is upon a plate that is to be worked at the copperplate press.
When the engraving is ready, the etching varnish through which
the drawing is cut is covered with a conducting substance, and an
electrotype plate is deposited upon the etching. When this is re-
moved from the mould it requires to be trimmed, for it is impos-
sible to etch a plate, or to bite the etching, so that all the lines shall
be exactly of the same depth. To remedy this the face of tha
electrotype is levelkd by grinding and burnishing. The following
instructions for artists are published by the patentee :
INSTRUCTIONS ON GLYPHOGRAPHY FOR THE AMATEUR. — " The
amateur must remember that he is producing a work of art for the
surface press, and not for copperplate printing.
" The drawing or etching should not be made with lines of
equal thickness in all the tints. If it is so treated with a thick line,
and if the cross hatching be kept of the same strength as the prin-
cipal line, it will appear like a coarse pen-and-ink drawing. If it
is treated in the above manner with a fine line, and the work laid
very close, it will have the appearance of one of the old etchings.
The amateur, therefore, will do well to remark, that it is only by a
ELECTROTYPE PROCESSES. 567
judicious mixture of bold and delicate work that beauty of style
can be obtained ; and as the darkest shades are generally foremost,
and become gradually lighter to the distance, so that the darkest
or nearest tones should generally be formed by the boldest work,
and gradually increase in delicacy to the offscape.
"Etching is a process nearly resembling drawing with a very
fine pen or pencil, and should be proceeded with as follows :
"Having obtained a polished copper-plate with an etching ground
properly laid, proceed to put your design upon the plate.
"If it is a print or miniature that is being copied, you must
make' a sketch or tracing of the same with a black lead-pencil: it
must then be traced on to the plate, remembering always, that the
proof from the block will be in the same position as the etching;
and that nothing must be etched or written backwards, as for the
ordinary copperplate printing.
" In order to trace the object on to the plate, take a piece of
transfer paper,* place it face downwards upon the plate, secure the
corners with a piece of wall wax or paste, or hold it steadily down,
if there is not much to trace ; then place on your sketch or trac-
ing, go over the outline with your etching-needle or a very hard
black lead-pencil, removing a corner at a time to see that all is
correctly transferred, and nothing omitted, or that the outline be
not too heavy and thick, in which case you must trace lighter.
"Having thus got your subject, as it were, sketched upon the
plate, proceed in all respects with your etching-needle as if making
a drawing with a black lead-pencil, only working more firmly,
taking care always slightly to cut the copper.
"Be careful not to try to form the dark touches and the black
parts of the subject -with a number of lines crossing and recrossing
each other, but scrape them away entirely with the point of your
penknife, or any other convenient instrument.
" In commencing the etching of a view, it is usual to begin with
the offscape, etching the same as neatly and as close as the nature
of the printing will admit, working more firmly and boldly in every
progressive tone, until you reach the foreground. In portraits it
is usual to commence with the eye ; and in draperies at the top,
working downwards.
" Owing to the great difference, between surface and copperplate
printing, depth of tone should be sought as much from the breadth
or thickness of the lines, as from laying them close together ; and
on the contrary, lightness of tint must be obtained by the distance
of the lines from each other, as well as from their delicacy.
" If you make a false line, or wish to efface any portion of the
work, a little Brunswick black (which can be procured at most oil
and color shops), spread thinly, may be used to stoo it out ; or rub
* To prepare the transfer paper, take some thin post or tissue paper, rub
the surface well with black lead, vermilion, red chalk, or any coloring matter:
wipe this preparation well off with a piece of clean rag, and it will be ready
for use.
568 THE PRACTICAL METAL- WORKER'S ASSISTANT.
a little of the superfluous ground from the side of the plate with a
earners hair pencil and turpentine: when this is dry the work can
be re-etched and finished at pleasure."
This last process has afforded some excellent work in the shape
of maps, among which we may cite the Penny Atlas, published by
Messrs. Chapman and Hall. Among subjects of a more pictur-
esque nature executed by glyphography, we may instance Mr.
Greo.rge Cruikshank's etchings of The Bottle. These are sufficient
to show that the art of electrotyping engravings, though yet in its
infancy, promises to be hereafter of importance in the line arts.
COPYING OF COPPERPLATE ENGRAVINGS. — Copperplate engrav-
ings, of all sizes, and of every degree of excellence, have been
copied by electrotype. The process is exactly the same as that of
making a copy of a penny -piece, as described at page 533 ; namely,
an electrotype mould is first made in copper, on which, of course,
the engraving appears in relief; upon which mould any number of
electrotype copies of the copperplate engraving may be deposited
successively. The duplicates thus made are accurate copies of the
original engraving; but they are rapidly worn away by the friction
they undergo in the ordinary process of copperplate printing. The
process has therefore not displaced the. use of engravings on steel.
COATING OF GLASS AND PORCELAIN. — This is done by putting
a fine coating of copal varnish over the glass, then black-leading
it, and depositing the copper. Another method has been proposed,
namely, to make a varnish of two parts asphaltum and one part
mastic, by fusing these together, and, when cool, dissolving the
mixture in spirits of turpentine to a syrup consistence. To pre-
vent the deposit coming off* the glass, the vessel is first corroded
by the fumes of hydrofluoric acid. A solution of gutta percha or
benzole has also been proposed as a varnish for fixing on the
black-lead and deposit.*
Retorts, basins, and other chemical vessels, are sometimes cov-
ered with copper for their protection during boiling and evapora-
tion. China saucepans have also been made and covered with
copper to take the place of tinned copper vessels, but the adhesion
of the metal upon these substances, even when we attempt to secure
it by the means above referred to, is never so perfect but that after
a short use the deposit of copper loosens from the vessels. There
is then great liability for liquids to get between the coating arid
the vessel, and when heat is afterwards applied these liquids satu-
rated with verdigris boil out. Consequently such coverings are
not well adapted either for culinary purposes or delicate chemical
operations. They have, notwithstanding, been ^highly recom-
mended, and the practice of covering the bulbs of large plain re-
torts., etc., may be useful in a few large manufacturing operations,
but our experience is certainly not favorable to their general use.
Mr. John Ridgway, of Cauldon-place, Staffordshire, china manu-
* Progress of General Science, vol. ii. ; and Pharm. Journal, vol. viii.
ELECTROTYPE PROCESSES. 569
facturer, has recently patented certain improvements in the method
or process of ornamenting or decorating articles of glass, china,
earthenware, or other ceramic manufactures. In the specification
of his patent, just enrolled, Mr. Ridgway states that his first object
is to apply a new glaze, which shall enable the metallic coating to
adhere firmly, by capillary attraction, and give affinity for copper
as a first coating. In pursuance of this, he first submits the
article to an alcoholic solution, or a gelatinous solution. He then
brushes over it an impalpable powder, composed of half carburet
of iron, and half sulphate of copper. The article thus treated is
then to be corroded by the fames of hydrofluoric acid. The article
is then to be smoothed, by brushing it over with silver sand, or by
the scratch-brush ; but when the shape and nature of the article
will not admit of this, it is to be plunged into a liquor, consisting
of 6 quarts sulphuric acid, 4 quarts aquafortis, } oz. muriatic acid,
and 6 quarts water. Grease is to be carefully removed from the
article, and a thin film of mercury is to be applied. The solution
of copper consists of 1 sulphate of copper, and 4 filtered water.
Suitable solutions for silvering or gilding are to be applied, in ac-
cordance with the practice of electrotyping. The claim is not to
the solutions the coating as such, but to the application of " elec-
trotyping," or electro-metallurgy, to the objects stated in the title,
provided the articles be so prepared as to allow them to combine
from an alloy with them.
ON GALVANIC SOLDERING. — Among the many applications of
the deposition of metals, there is one we have been often asked
about, namely, if it would not be possible to solder different metals
together by that process. The following article, which is taken
from the Technologist, will give a full reply to all who may be
still inquiring for this application:
" Under the name of galvanic soldering, a process is known by
means of which two pieces of metal may be united by means of
another metal, which is precipitated thereon through the agency
of a galvanic current. This mode of soldering by the ' wet
method' has been often recommended in various periodicals relating
to the industrial arts ; but it has been objected that, practically
speaking, the union between two pieces of metal could not be
effected by means of a metal precipitated by galvanic agency. In
order, however, to arrive at a definite conclusion upon this ques-
tion, M. Eisner undertook the following experiments, the results of
which are in favor of the practical use of the operation of solder-
ing by galvanic agency. In conducting these experiments, the
kind of battery known as Daniell's 'constant battery' was em-
ployed ; and upon the end of the copper wire, which formed the
negative electrode, a strong ring of sheet-copper was placed. This
ring was cut asunder at one point, and the distance left between
the several parts was about the sixtieth of an inch. At the end
of a few days (during which time the exciting liquors were sev-
eral times i -'.newjd) the space in the severed portion of the ring
570 THE PRACTICAL METAL-WORKER'S ASSISTANT.
was completely filled up with copper regulus, which had been pre-
cipitated ; and on partially cutting with a file through the part
thus filled up, and examining it with a lens, it was observed to be
very equally filled with solid and coherent copper.
"Another copper ring was then cut into two parts, and the two
semi-angular segments thus obtained were placed with the Taees of
the sections opposite each other, and submitted to the action of a
galvanic current. At the end of a few days, the segments were
united by the copper precipitated, thus forming again a complete
ring. It was also found in this case, on removing with a file a
portion of the thickness of the ring at the points of contact, that
the spaces had been completely filled up by copper galvanically
precipitated, which had united the whole. On observing these
points carefully with a lens, the regular deposition of the copper
could be readily traced between the formerly separated portions of
the ring.
"A third experiment was made in the following manner : Two
strong rings of sheet-copper were laid with their freshly-cut faces
one upon another, so that the two rings constituted a cylinder.
These rings were surrounded by a band of sheet-tin which was
coated with a solution of wax, so that the two rings were equally
surrounded by a conducting material. Thus disposed, these rings
were attached to the negative wire of the battery and immersed
in the bath of sulphate of copper. At the end of a few days the
interior surface of the rings was covered with precipitated copper,
and between the contact surfaces of the two rings copper was also
precipitated. These rings had only been submitted to the gal-
vanic current to such an extent as to cover their interior surface
with a thin coating of precipitated copper, and yet they were
already completely re-united, and formed a cylinder consisting of
a single piece. The exterior conducting covering, consisting of
a sheet of tin, was of course removed before testing the cohesion
or persistence of the galvanic precipitate. It may be remarked
that these rings, after being for a certain time in contact (during
the galvanic action), together with the plate of copper upon which
they rested, became so encrusted with precipitated metallic copper
that some force was found necessary to effect their detachment
from the copper wire.
"There would appear to be no doubt, then, according to the
results obtained in the preceding experiments, that two pieces of
metal may be firmly united by means of galvanically-precipitated
copper : in a word, that soldering by galvanic agency is perfectly
practicable. It will therefore be possible to firmly unite the dif-
ferent parts of a large piece of metal, and to make a perfect figure
of them by galvanic precipitation of a metal (copper, in ordinary
cases). If solutions of salts of gold or silver were employed in as
concentrated a form as those of copper above mentioned, there is
reason to believe that galvanic soldering would also result. In
fact, M. de Hackewitz states that in some experiments on a larger
ELECTROTYPE PROCESSES. 571
scale Vhich ne undertook, to obtain hollow figures by galvano-
plastic means, he had remarked that galvanic union often took
place between the pieces operated upon. M. Eisner states that
while conducting the experiments above-mentioned, he remarked
that by employing too powerful a current, the negative electrodes
of copper, and even the plate of copper, and ring of the same metal
resting thereon, became covered with a deep brown substance, in
the same manner as this occurs under similar circumstances in gal-
vanic gilding, as is well known. After several unsuccessful
attempts to prevent the formation of this brown coating, M. Eisner
found that it was possible to remove it entirely on immersing the
articles covered therewith during a few seconds in a mixture of
sulphuric and nitric acids. By this means the precipitated copper
was made to assume its natural red color. The possibility of prac-
tically effecting the operation of soldering by galvanic agency may
be explained in a few words, in a theoretical point of view. The
article is in fact in an electro-negative state of excitation, whilst
the zinc operates positively. The result is, that the faces which
are placed opposite each other, when the ring has been cut, are
negative ; that is to say, in an electric condition of the same de-
nomination. During the progress of the electrolytic decomposition
of the metallic salt in solution (sulphate of copper in the above
case), the electro-positive molecules of copper which are detached
.simultaneously arrange themselves upon the two opposite faces,
and in the direction of the break. Now, from the moment that
these molecules are deposited, they constitute with the piece a
homogeneous mass, and from that time act negatively upon the
copper which is contained in the solution, and again precipitate
copper in the form of regulus. This method of operation con-
tinues until the space which existed between the two separate
pieces of metal is filled up with metallic copper — in fact the layers
of copper which become deposited in an equal manner upon the
contiguous faces of the metal gradually diminish the distance which
separated the latter, until at length the metallic layers which cross
in the opposite direction meet each other ; the result being, that
the whole of the break which originally existed between the faces
will have disappeared and become filled up with copper.
" With respect to the solidity (the degree of cohesion) of the
galvanic soldering, it is the same as that of copper or other metal
precipitated by galvanic agency. It will moreover be well under-
stood that too energetic galvanic excitation must have an injurious
influence upon the cohesion of the metal precipitated ; and in this
case precisely the same phenomena will be observed as those which
have long manifested themselves in ordinary galvano-plastic oper-
ations."— L. ELSNER, Technologist.
We mention another application of the electro deposition, which
might be extended.
GALVANO-PLASTIC NIELLO. — Niello, a peculiar style of enamel-
ling, consists in engraving or stamping figures on a plate of silver
572 THE PRACTICAL METAL-CORKER'S ASSISTANT.
or gold, and then filling the incised lines or impressed pattern with
a sort of enamel — differing, however, from true enamel — which is
a kind of glass, by being formed of a mixture of the sulphurets
of lead, silver, and copper. This mixture is of a black color —
hence the name niello, from nigellum. derived from niger, black —
and when melted into the intaglio parts of a plate gives it some-
what the appearance of an inked engraved copperplate. A new
kind of niello work has lately been introduced on the Continent,
in which, however, the figures are not produced by an enamel of
sulphuret of silver, as in the true niello, but by a different-colored
metal ; thus on a plate of gold may be produced fine engravings,
the lines of which are in silver, and so on. This can be effected
in two ways : first, by covering the plate to be ornamented with a
varnish exactly as is used in etching ; the pattern or ornament is
then to be engraved on this varnish, and the metallic surface
etched out to the proper depth. The engraved plate is to be
placed in a solution of the metal intended to form the pattern, and
a deposit allowed to form in the usual way adopted in all galvano-
plastic works. When the intaglio lines have been completely
filled up by the deposited metal, the plate is removed from the
solution and ground, when the pattern will be fully developed.
The second method consists in sketching the ornament on a sheet
of paper with lithographic ink, placing this, with the side upon
which the drawing was made, upon a plate of silver or other metal
to be ornamented, and pressing them together ; the paper is now
removed with water, slightly acidified, leaving the ink adhering to
the plate, which is to be sprinkled with sand. When the ink has
fully dried, the sand is blown away ; the plate is placed in a solu-
tion of the metal which it is intended should form the ground, and
put in connection with the battery. By this means a deposit will
be formed over the whole surface, except the parts protected by
the ink. On the removal of the latter with alcohol or spirits ot
turpentine, etc., the original metal will be exposed, forming a pat-
tern. Many highly ornamental and useful applications might be
made of these processes, especially in the manufacture of church
furniture. Instead of simply engraving the name and legend upon
pieces of plate presented to persons, it might be put in in letters
of gold at very little more expense.
CHAPTER XXVIII.
BRONZING.
WE have already mentioned that when a medal has been made
from a metallic mould, protected by a little wax dissolved in tur-
pentine, it retains its bright copper lustre for a long time, even
BRONZING. 573
when exposed to the air; but generally the copper medals and other
objects are very liable to tarnish, for which reason it is usual to
give them a coating of bronze, that they may acquire a permanently
agreeable appearance.
BROWN BRONZES. — Bronzing is effected by several very simple
methods, the most common of which is the following :
Take a wine-glass of water, and add to it four or five drops of
nitric acid ; with this solution wet the medal (which ought to have
been previously well cleaned from oil or grease) and then allow it
to dry ; when dry impart to it a gradual and equable heat, by which
the surface will be darkened in proportion to the heat applied.
ANOTHER METHOD. — Make a thin paste of crocus and water : lay
this paste on the face of the medal, which must then be put into an
oven, or laid on an iron plate over a slow fire ; when the paste is
perfectly reduced to powder, brush it off' and lay on another coat-
ing ; at the same time quicken the fire, taking care that the addi-
tional heat is uniform ; as soon as the second application of paste is
thoroughly dried, brush it off'. The medal being now effectually
secured from grease, which often occasions failures in bronzing,
coat it a third time, but add to the strength of the fire, and sustain
the heat for a considerable time: a little experience will soon enable
the amateur to decide when the medal may be withdrawn ; the third
coating being removed, the surface will present a beautiful brown
bronze. If the bronze is deemed too light the process can be
repeated.
Another very simple method is this : after the medal is well
cleaned from wax or grease, by washing it in a little caustic alkali,
brush some black lead over the face of it, and then heat it in the
same way as described for crocus ; or a thin paste of black lead may
be used, and the processes already referred to be repeated until the
desired brown tint is obtained. In this kind of bronze a little
Hematitic iron ore, which has an unctuous feel, may be brushed
over the face of the bronze, by which a beautiful lustre is imparted
to it, and a considerable variety in the shade may be obtained. In
the brown bronzes the copper is slightly oxidized on the surface.
BLACK BRONZES. — A very dark colored bronze may be obtained
by using a little sulphuretted alkali (sulphuret of ammonia is best).
The face of the medal is washed over with the solution, which
should be dilute, and the medal is to be dried at a gentle heat. It
should afterwards be polished by a hard hair brush. Sulphuretted
hydrogen gas is sometimes employed to give this black bronze,
but the effect of it is not so good, and the gas is very deleterious
when breathed. In these bronzes the surface of the copper is con-
verted into a sulphuret.
Many metallic solutions, such as weak acid solutions of platinum,
gold, palladium, antimony, etc., will impart a dark color to the
surface of medals when they are dipped into them. The medal
after being dipped into the metallic solution is to be well washed
and brushed. In such bronzes the metals contained in the solu-
I
574: THE PRACTICAL METAL-WORKER'S ASSISTANT.
tion are precipitated upon the face of the copper medal, which
effect is accompanied by a partial solution of the copper.
GREEN BRONZES. — Green bronzes require a little more time than
those already described. They depend upon the formation of an
acetate, carbonate, or other green salt of copper upon the surface
of the medal. Steeping for some days in a strong solution of com-
mon salt will give a partial bronzing which is very beautiful, and
if washed in water, and allowed to dry slowly, is very permanent.
Sal ammoniac may be substituted for common salt. Even a strong
solution of sugar, alone, or with a little acetic or oxalic acid, will
produce a green bronze; so also will exposure to the fumes of dilute
acetic acid, to weak fumes of hydrochloric acid, and to several
other vapors. A dilute solution of ammonia allowed to dry upon
the copper surface will leave a green tint, but not very permanent.
Electrotypes may also be bronzed green, having the appearance
of ancient bronze, by a very simple process: take a small portion
of bleaching powder, place it in the bottom of a dry vessel, and
suspend the medal over it, and cover the vessel : in a short time
the medal will take on a green coating, the depth of which may be
regulated by the quantity of bleaching powder used, or the time
that the medal is suspended in its fumes : of course any sort of
vessel, or any means by which the electrotype may be exposed to
the fumes of the powder, will answer the purpose : a few grains of
the powder is all that is required. According as the medal is
clean or tarnished, dry or wet, when suspended, different dints
with different degrees of adhesion will be obtained.
The green bronzes are generally applied to figures and busts.
These directions and hints will enable the student to vary his
bronzes. Practice will give him perfection, and enable him to fix
upon that which best pleases his taste. Scarcely two electrotypists
agree upon the same method of bronzing, but differ in some little
details of practice, or on some point of taste. Each prefers the
plan that has given to him his best results, and which he can
hardly impart by description to another.
Should the electrotypist wish to coat the copper medal with
another metal, as silver .and gold, directions will be given under
plating and gilding how to proceed to effect his purpose.
CHAPTER XXIX.
DEPOSITION OF METALS UPON ONE ANOTHER.
COATING OF IRON WITH COPPKR. — Besides making articles of
solid copper, we may at a small cost give a coating of copper to
aoother metal, such as iron, which if kept in a dry place, will retaiu
COATING OF IRON WITH CGf'tR. 575
the appearance of copper for any length of time. But in covering
iron with copper, or any one metal with another, great care must be
taken that a proper kind of solution be used.
It is a familiar fact, that if a piece of iron, such as the blade of a
knife, be dipped into a solution of sulphate of copper, it receives a
coating of that metal. This is often described as the result of gal-
vanic action, but there is no more galvanic action in this than in
any ordinary chemical combination ; it is simply a case of chemical
substitution ; the acid that is in union with the copper having a
stronger attraction for iron, leaves the copper, and combines with
the iron: the copper is left on the surface of the iron, but the two
metals not having sufficient polar attraction to cause them to adhere
so firmly as to exclude the action of the acid, the copper is under-
mined, and falls to the bottom of the solution as a powder. After
some copper has fallen upon the surface of the iron, local galvanic
action is induced between it and the iron ; but this secondary
action is altogether distinct from that which first takes place.
Any solution that has the power to give a metallic coating to a
metal when dipped into it, should not be used to coat that metal
by electricity.
The attraction of the common mineral acids for the ordinary
metals is as follows : Zinc, iron, copper, nickel, silver, gold, pla-
tinum.
If the metal to be deposited be copper held in solution by an
acid, say sulphuric acid, then iron or zinc cannot be coated with
copper from this solution ; the acid having a greater attraction for
these metals, will leave the copper and combine with them as de-
scribed above : but if the metal to be coated be any of those under
copper, in the above table, then no chemical action will take place,
and no deposit will be made, except as the effect of the electric
current introduced by the battery. This we believe is the cause
why De la Kive, Spencer, and others, failed, at an early stage of
the art, in their experiments in plating and gilding, as they em-
ployed acid solutions, which are quite impracticable when used for
depositing upon inferior metals. Under these circumstances, other
solvents for the metals must be used, which have a different rela-
tive attraction for the metals than the acids have. The substance
first applied for this purpose is, after sixteen years experience, still
found to be the best — namely, cyanide of potassium.
CYANIDE OF POTASSIUM. — This substance may be prepared by
exposing ferrocyanide of potassium (yellow prussiate of potash) to
a red heat in an iron crucible; then pounding the mass, and boil--
ing it in alcohol of about spec. grav. 0'900: cyanide of potassium
crystallizes on cooling the resulting solution. It is now, however,
almost universally prepared for electro-metallurgical purposes, by
a process which was first suggested by Messrs. F. and E. Rodgers.
but afterwards more fully explained by Professor Liebig, and hence
called "Liebig's Process:" it is at once both simple and easy of
performance.
576 THE PRACTICAL METAL-WORKER'S ASSISTANT.
Ferrocyanide of potassium rxmnded fine, is dried over a slow
fire (we have found an iron plate, or clean shovel, to serve the pur-
pose very well) : it must be constantly stirred to prevent its form-
ing a cake upon the hot iron; when perfectly free from moisture, 8
parts must be thoroughly well mixed with three parts of carbonate
of potash, also well dried: put a cast-iron crucible into the fire, and,
when it is red hot, nearly fill it with the mixture, and keep up the
heat by occasional augmentations of fuel : the crucible should be
kept covered as much as possible. In a short time the whole fuses
into a beautiful liquid with the evolution of gas. It should be kept
in this state for 10 or 15 minutes, being occasionally stirred with
an iron rod : the portion adhering to the red should be examined
from time to time, and when the liquid on it cools white, it is an
indication that it is ready to be removed from the fire ; but the first
time a cast-iron crucible is used, this test will not be so accurate,
khe salt having then a light gray color. When the crucible is
removed from the fire, it should be placed upon a stone, the mass
stirred, and then allowed to settle for a short time, after which the
clear, or liquid part, is to be poured off into a clean iron vessel.
The sediment should be scraped clean out of the crucible while it
is hot, as the crucible will do to use again several times ; but if the
mass at bottom be allowed to cool it will be difficult to remove it
from the crucible afterwards. The clear liquid poured off is cyanide
of potassium, having from 25 to 30 per cent, of cyanate of potash,
and other impurities generally contained in commercial yellow
prussiate of potash : 80 per cent, of cyanide of potassium is the
greatest proportion that this process can give. We have occa-
sionally obtained it at 78 per cent, from commercial materials, but
more generally at 70 and 72 per cent ; and we have found cyanide
of potassium in the market containing as little as 49 per cent, of
pure cyanide.
The results of the manufacture of this salt on a large scale, from
the ordinary materials of commerce, show that 55 Ibs. of yellow
prussiate, dried as directed above, yield 48 Ibs. ; and 19 Ibs. of
carbonate of potash give 18 Ibs. of dry salts; in all 66 Ibs. of the
proper mixture. The crucible used was of this shape,
Fig. 579, capable of holding from two to three pints ; FiS- 579-
in general two of them were used up in making the
above quantity of cyanide, even when great care was
taken. One great cause of the crucible giving way is
the depth of the fire, and openness of the bars of the
grate. The bottom of the crucible, between each pair
of bars, fuses from the great heat concentrated near the opening.
To remedy this evil, a square tile of fire-clay should be laid upon
the bars upon which the crucible is to rest. The tile must not.
cover all the bars, else the draught will be stopped — an equal
space must be left at each side of the tile, whic'h will preserve a
regular heat around the crucible.
The quantity of 'clean cyanide of potassium obtained from the
COATING OF IRON WITH COPPER. 577
above quantity of materials was about 38 Ibs.; the sediment
scraped out of the crucible, being put into water, yielded about 6
Ibs. more in solution, but of inferior quality — good enough, how-
ever, for precipitations, the cleaning of silver, and other general
purposes in the factory.
It may be mentioned that in these operations the crucible is
never allowed to cool, but as soon as the sediment is scraped out,
it is again put into the furnace. If the iron sediment is not well
cleaned out, it imbibes oxygen rapidly, and the charge next taken
from the crucible will have an excess of cyanate of potash, besides
lessening the capacity of the crucible. Generally speaking, how-
ever, even when the utmost care is taken, the last charge has more
cyanate of potash than the first.
CYANIDE OF^COPPER. — To prepare copper solutions by means
of cyanide of potassium, for covering iron and other positive
metals, there are several methods.
First Method. — To a solution of sulphate of copper, add by de-
grees a solution of cyanide of potassium, which will give a yel-
lowish green precipitate, with slight effervescence. There will be
evolved a gas, having a most pungent odor, to prevent the inhala-
tion of which the most watchful carefulness has to be exercised, as
it is very deleterious. It will be found that the copper is not all
precipitated by the cyanide of potassium, for according to this
mode, when a precipitate ceases to be formed, the solution remains
greenish blue, probably owing to the decomposition of the cyanate
of potash, and the formation of ammonia, which holds copper in
solution, and forms also some complicated compounds with the
cyanides of copper. If cyanide of potassium is added until the
blue solution disappears, still copper is held in the solution, and
may be detected by taking out a little, and adding to it a few drops
of sulphuric acid, which will give a white precipitate of subcyanide
of copper. The loss of copper sustained is the only objection to
this mode of preparing a copper solution. The cyanide of potas-
sium is added until a precipitate is no longer formed ; it is then
allowed to settle, the clear liquid is poured off, and the vessel is to
be filled with water : when the precipitate has again settled, the
liquor is poured offj and this washing is repeated four or five times,
in order to wash out the sulphate of potash which is formed during
the precipitation. After being thus washed, a solution of cyanide
of potassium is added to the precipitate until it dissolves. The
coppering solution is now complete : it is of a light yellow color,
and is well adapted for ordinary purposes. The loss of copper is,
however, considerable, being about one-fifth of the whole.
Second Method. — A coppering solution may also be prepared by
adding cyanide of potassium, to oxide of copper, or to carbonate
of copper, until it is dissolved. But these solutions are objec-
tionable, the latter especially so, as it contains a great quantity of
carbonate of potash, formed from the mutual decomposition of the
carbonate of copper and cyanide of potassium, and the carbonate
37
578 THE PRACTICAL METAL- WORKER'S ASSISTANT.
of potash deteriorates the solution ; the former leaves potash in
the solution, but this is not so bad as the carbonate of potash.
Third Method. — The method we have adopted in manufacturing
purposes is as follows : — To a solution of sulphate of copper, we
add a solution of ferrocyanide of potassium, so long as a precipi-
tate continues to be formed: this is allowed to settle, and the clear
liquor being decanted, the vessel is filled with water, and wher
the precipitate settles, the liquor is again decanted, and we con-
tinue to repeat these washings until the sulphate of potash is
washed quite out. This is known by adding a little chloride of
barium to a small quantity of the washings, and when there is nc
white precipitate formed by this test, the precipitate is sufficiently
washed. A solution of cyanide of potassium is now added to this
precipitate until it is dissolved, during which probess the solution
oecomes warm by the chemical reaction that takes place. The
solution is filtered, and allowed to repose all night. If the solu-
tion of cyanide of potassium that is used is strong, the greater
portion of the ferrocyanide of potassium crystallizes in the solu-
tion, and may be collected and preserved for use again. If the
solution of cyanide of potassium used to dissolve the precipitate is
dilute, it will be necessary to condense the liquor by evaporation,
to obtain the yellow prussiate in crystals ; the remaining solution
is the coppering solution. Should it not be convenient to separate
the yellow prussiate by crystallization, the presence of that salt in
the solution does not deteriorate it, nor interfere with its power of
depositing copper.
PECULIARITIES IN WORKING CYANIDE OF COPPER SOLUTION. —
The true composition of the salts thus formed by copper and
cyanide of potassium has not yet been determined, being both
various and complicated, but their relations to the battery and
electrolyzation are peculiar. The solution must be worked at a
heat of not less than from 150° to 200° Fahrenheit. All other
solutions we have tried follow the laws laid down by Spencer and
Smee, namely, that if the electricity is so strong as to cause gas to
be evolved at the electrode, the metal will be deposited in a sandy
or powdered state ; but the solution of cyanide of copper and pot-
assium is an exception to these laws, and there is no reguline de-
posit obtained unless gas is freely evolved from the surface of the
article upon which the deposit is taking place. This necessitates
the use of batteries of several pairs intensity, varying from five tc
nine pairs of Wollaston's battery, according to the heat and the
state of the solution.
As this solution is used hot, a considerable evaporation takes
place, which requires that additions be made to the solution from
time to time. If water alone is used for this purpose, it will pre-
cipitate a great quantity of copper as a white powder, but this is
prevented by dissolving a little cyanide of potassium in the water
at the rate of about four ounces to the gallon. The vessels used
?n factories for this solution are generally of copper, which are
COATING OF IRON Wl H COPPER. 579
heated over a flue, or on a sand-bath — the vessel itself serving as
the positive electrode of the battery ; but any vessel will suit if a
copper electrode is employed, when the vessel is not of copper.
PREPARATION OF IRON FOR COATING WITH COPPER. — When it
is required to cover an iron article with copper, it is first steeped
in hot caustic potash or soda, to remove any grease or oil. Being
washed from that, it is placed for a short time in dilute sulphuric
acid, consisting of about one part of acid to sixteen parts of water,
which removes any oxide that may exist. It is then washed in
water, and scoured with sand till the surface is perfectly clean, and
finally attached to the battery, and immersed in the cyanide solu-
tion. All this must be done with despatch, so as to prevent the
iron from combining with oxygen. An immersion of five minutes
duration in the cyanide solution is sufficient to deposit upon the
iron a film of copper. But it is necessary to the complete protec-
tion of the iron, that it should have a considerable thick coating :
and, as the cyanide process is expensive, it is preferable, when
the iron has received a film of copper by the cyanide solution, to
take it out, wash it in water, and attach it to a single cell or weak
battery, and put it into a solution of sulphate of copper. If there
is any part not sufficiently covered with copper by the cyanide
solution, the sulphate will make these parts of a dark color, which
a touch of the finger will remove. When such is the case, the
article must be taken out, scoured, and put again into the cyanide
solution till perfectly covered. A little practice will render this
very easy. The sulphate solution for covering iron should be pre-
pared by adding to it by degrees a little caustic soda, so long as
the precipitate formed is re-dissolved. This neutralizes a great
portion of the sulphuric acid, and thus the iron is not so readily
acted upon.
EFFECTS OF CONDUCTING POWER IN SOLUTIONS AND METALS. —
In covering iron, platinum, or such comparatively bad-conducting
metals, with other metals that are good conductors, or the solutions
of which are good conductors, the property of conduction in rela-
tion to the solution is beautifully illustrated. If we take a copper
wire, say 8 or 10 feet long, one end of which is attached to the
zinc of a battery, and laid parallel with the positive electrode into
a solution for the purpose of receiving a deposit, it will be found
that the greatest amount of deposit has taken place at the end
furthest from the battery : but if an iron or platinum wire be sub-
stituted for the copper one, the contrary result will take place ; for
the end furthest from the battery will be the last to receive the
coating, and will have the least quantity of metal deposited upon
it. If the copper wire was 30 feet long, little alteration would be
seen in the deposit ; but upon an iron or platinum wire of that
length the deposit proceeds only a certain distance, and no deposit
will take place on the end furthest from the battery unti1 the cur
rent has passed a considerable time, after which the Deposit is
observed to advance gradually. The copper as it becomes deposited
580 THE PRACTICAL METAL -tt C JvRER's ASSISTANT.
on the iron acts as a conductor, transmitting the deposit further
onwards to its final point, as well as adding to the deposition already
effected upon the iron. The length of deposit that would be formed
on the first immersion of the wire depends upon the conducting
power of the solution ; for, as already stated, solutions vary in this
property as well as metals. We have found that a few feet of iron
wire offer a greater resistance to the passage of the current than
the solution between the iron wire and the positive electrode, which
is only about 2 or 3 inches ; but their exact relations to each other
we have not yet had an opportunity of investigating.
Under these circumstances, it may be asked, why not increase
the intensity of the battery, and so force it along the wire ? But
this, as will be apparent, can only be done within certain limits ;
for by increasing the intensity of the battery it may be rendered
too strong for the solution near the battery, and thus a sandy
deposit will be given at the one end and none at the other. The
electro-metallurgist, when coating long rods of iron wire with any
metal, has to make connections with the battery every few feet.
The wire is generally coiled up in the form of a cork-screw, and
suspended by copper wires. We have found it very convenient to
coil it upon a reel, having its armatures tipped with copper, and
connected with the battery. This plan insures a regular coating,
but the position of the wire requires to be changed during the
operation, otherwise the parts which press upon the arms of the
reel will be left without deposit.
ILLUSTRATION OF CONDUCTION. — As an illustration of the prop-
erty of conduction, we mention the following circumstance: — Hav-
ing a large iron shaft, or rod, about 12 feet long and 3 inches aver-
age diameter, to cover with copper, we had it properly cleaned,
placed in a hot solution of cyanide of copper and potassium, and
surrounded by sheets of copper as a positive electrode. Two bat-
teries of 7 pairs intensity were attached, one at each end of the
shaft ; but, by an oversight, one of the batteries was not properly
connected, the copper terminal of the battery having been attached
to the shaft. Had the shaft been of copper, the one battery would
have neutralized the other, so that there would not have been any
deposit; or, had the one battery been stronger than the other, there
would have been a current and deposit equal to the excess of power
of the one over the other. But, under the -tated circumstances, a
different result was obtained. After the batteries had been in
action two hours, we found that a beautiful copper coating was im-
parted to that half of the shaft which extended from the point prop-
erly connected, while the other half was quite bare — no deposit
having taken place upon it : but a deposit had been made upon the
copper electrode opposite this non-affected half. The batteries did
not (as we could perceive) affect one another, .except that the one
improperly connected prevented the deposit effected by the other
proceeding further than the half length of the shaft; but it made the
deposit obtained more perfect than would have been the case had
been only one battery at one end.
COATING OF IRON WITH OTHER METALS. 581
In this -instance, the distance of the shaft from the electrode was
6 inches, so that the resistance of 6 feet of the iron was more than
6 inches of the solution; hence the influence of the contra-acting
battery could not reach further: or if any power passed further it
was neutralized by the other battery — which we are inclined to
think did not take place — as the amount or thickness of deposit
upon the one half was fully more than we would have anticipated
upon the whole, had the batteries been properly connected.
NON- ADHERENCE OF DEPOSIT. — Objections have been made to
covering iron with copper for its protection, from an impression
that the copper will not adhere to the iron ; but if the operation is
carefully performed the copper will adhere ; when it does not, it
will generally be found that it is the copper deposited from the sul-
phate which loosens from the copper deposited from the cyanide —
occasioned no doubt, by the article not having been sufficiently
washed from the cyanide solution, and thus having a thin film of
cyanide of copper precipitated upon the surface, which prevents
the adhesion of the after deposit. Or, as it happens sometimes,
that the cyanide of copper solution has not much free cyanide of
potassium, and, consequently on putting the article into water, the
cyanide of copper is decomposed by the water, and precipitated
upon the surface. If a little cyanide of potassium is dissolved in
the first water used for washing out the depositing solution, this
will be prevented.
We have repeatedly deposited copper upon iron wire, and after-
wards had it drawn out to twice its original le»gth without the
copper striping off; but, as the copper becomes hard and brittle, it
is liable to break if the wire is much bent, and if it be made red
hot, to anneal or soften it, the copper will oxidize, and if the coat-
ing is thin, the iron will be left bare in some places. We have
seen iron bolts, covered with copper, driven through 17 inch wood,
and nails of all sizes subjected to rough work, without the deposit
being injured. Some iron work coated in 1842, and exposed to
the atmosphere, remains in good condition still. These remarks are
also applicable to iron covered with zinc. The coating of iron with
copper has been tried in a great variety of ways for large opera
tions, but in general these trials have, commercially, ended unsuccess
fully ; the labor and cost is greater than the advantages sought will
warrant for ordinary purposes. Many years ago trials were made to
cover cast-iron with copper, and then gild or plate for ornamental
use, but only with partial success. More recently, however, a patent
has been taken out for the same purpose, and which, being one of
these applications that would be useful in beautifying and improv-
ing the taste of the community, we give an abstract of the specifi-
tion as follows :
COATING CAST-IRON WITH OTHER METALS. — "Mr. W.Newton (foi
a correspondent) has patented the coating cast-iron permanently with
copper, by depositing the copper by galvanic action, from a solu
tion prepared by first taking a saturated solution of sulphate oi
582 THE PRACTICAL METAL-WORKERS ASSISTANT.
copper in water and precipitating with carbonate of potash, and
then re-dissolving in cyanide of potassium, whether the copper be
deposited directly on the surface of the cast iron, or on zinc previ-
ously deposited thereon. The second part of this invention con-
sists of coating cast-iron with the alloy of copper called brass, by
first coating the cast-iron with copper, or zinc, or both, and then
depositing the brass thereon, by galvanic action, from a solution
formed by mixing with the solution of copper employed in the first
part of the invention, a solution of zinc prepared in substantially
the same manner. The iron articles thus coated, may be subse-
quently coated with gold or silver, so as to give them the appear-
ance of these latter metals. The articles of cast-iron to be coated
or plated are first to be cleansed by what is known as thf 'pick-
ling' process, with dilute sulphuric acid, and then 'scratch brushed,'
as it is termed, to free the surface from scale, sand, and other foreign
substances which may not have been removed by the acid ; and
after this the castings are to be immersed in dilute mtro-muriatic
acid. Any other mode of thoroughly cleansing the surface may
be substituted for that above indicated. A solution of zinc is then
prepared in the following manner : — Dissolve the sulphate of zinc
in water until the water is saturated, and precipitate by means of
prussiate of potash. The precipitate is then collected in a filter,
and re-dissolved in cyanide of potassium. This constitutes solu-
tion number one. A solution of copper is then prepared in the
same manner, by dissolving sulphate of copper in water, and pre-
cipitating with carbonate of potash : this precipitate is dissolved in
cyanide of potassium, and is called the second or copper solution.
The third, or what may be termed the brass solution, is then pre-
pared by mixing together the first or zinc solution with the second
or copper solution, in such proportions as to produce the shade of
color required — increasing the proportional quantity of -the one or
the other at the discretion of the operator. The iron castings hav-
ing been thoroughly cleansed, are first immersed in the first or
zinc solution, and the galvanic battery applied in the usual man-
ner of electrotyping and continued until the required thick-
ness of zinc is deposited on the surface of and caused to unite
with the surface of the cast-iron, which is a carbonate of iron.
The castings thus coated or plated with zinc, are then to be
immersed in the second or copper solution, and the galvanic bat-
tery applied, as with the first or zinc solution, and continued until
the required thickness of copper shall have been deposited. In
this way it will be found that the copper coating has become
thoroughly attached to the zinc, and the zinc to the iron, so that
they cannot be removed except by filing or cutting, as in the case
of a solid mass of copper ; so that articles, of whatever form desired,
which can be made of cast-iron — that is, of carbonate of iron — can
be coated with copper, so as to answer nearly if not all the pur-
poses to which they could be applied if made of solid copper; thus
cjreatly economizing the cost. After the surface of cast-iron ha?
COATING OF IRON WITH ZINC. 583
been coated with zinc, or with, copper, or with zinc and then with
copper, which latter is much the best, if it be desired to coat it
with brass, it is to be immersed in the third or brass solution, and
the galvanic battery applied, until the required thickness shall
have been deposited. In doing this it is important that the posi-
tive pole of the battery should be made of brass, and as nearly as
practicable of the shade of the brass to be deposited; for if a cop-
per pole be applied, it will deposit in excess the copper portion of
the solution. If desired, the brass can be deposited on the coat-
ing of zinc instead of the coating of copper ; but it will be found
decidedly better to deposit the brass on the coating of copper,
whether the copper be deposited directly on the cast-iron or on a
coating of zinc, although the latter is the best. In this way articles
are produced, having all the appearance, and answering nearly if
not all the same purposes as if made entirely of brass, and at much
less cost. The cast-iron being thus coated with brass, the surface
may be bronzed in the usual and well-known manner of bronzing
brass ; and as the process of bronzing on brass and copper is well
known, it will be unnecessary to give a detailed description of it.
The surface of the cast-iron being thus coated with brass, or with
copper, can then be coated eifectually with silver or gold in any of
the well known modes of coating brass or copper with those fine
metals ; it will not, however, be necessary to give the details of
such mode or modes, as they are well known in the arts. The
patentee, remarks that it will be found better to deposit th.e silver
or gold on the brass coating than on the copper coating, on account
of the color — particularly when, from reasons of economy, it is
desired to make the coating of fine metal very thin. The patentee
claims the process herein described, or any mere modification
thereof, for coating cast-iron (carbonate of iron) with copper, by
causing the copper, from a solution such as above described, to
deposit, by galvanic action, directly on the surface of the cast-iron,
or on the zinc previously deposited thereon, as set forth. And
also the process herein described, or any mere modification thereof,
for coating cast-iron with the alloy of copper, known as brass, by
causing the brass, from a solution such as above described, to
deposit, by galvanic action, on to the surface of the cast-iron, pre-
viously coated with zinc, or copper, or both, as specified."
COATING OF IRON WITH ZINC. — In covering iron with zinc, the pre-
cautions necessary for copper are not required: zinc being the posi-
tive metal, acids have a stronger affinity for it than for iron, and
therefore an acid solution may be used. The one generally used
is the sulphate.
SULPHATE OF ZINC. — Zinc dissolves easily in sulphuric acid, and
the solution by evaporation yields crystals of sulphate of zinc ; but
as the salt is very cheap and abundant in the market, it is more
convenient and economical to buy than to make it. The solution
for depositing is made by dissolving 2 Ibs of the crystallized salt
in one gallon of water. The single cell process cannot be used
584 THE PRACTICAL METAL-WORKER'S ASSISTANT.
advantageouslv with this solution. A separate battery is necessary,
and a zinc positive electrode. The metal is very easily deposited
— one or two pairs of Wollaston's battery being sufficient for coat-
ing small articles.
Zinc may be deposited upon black-leaded surfaces in the same
manner as copper ; but, unless more than ordinary precautions are
observed, an article formed in this manner is so brittle that it can
hardly be handled without breaking, from its crystalline character.
When the deposition upon black-lead is attempted, the best method
is to have the solution saturated with salt, employing a battery of
six or seven pairs of plates, and keeping the articles on which the
deposit is taking place constantly in motion.
The use of cyanide of zinc has been recommended, but for what good
reason it is hard to know. It is unnecessary, and its use presents great
practical difficulties. The positive electrode becomes coated, after a
few minutes working, with a white pasty matter which prevents
further action and stops the current. Some of this white coating
collected, washed, and dried in the air, gave by analysis,
Oxide of ziuc 51*3
Cyanogen T7
Iron trace
Potash 2-3
Carbonic acid 27'8
Aiatter insoluble in HC1. . . . 2*5
Water . 14*8
1004
The zinc is converted into carbonate of zinc : the potash is com-
bined with the cyanogen as cyanide of potassium.
USE OF ZINC COATING. — The principal application of zinc is
upon iron, to protect it from corrosion, which it does, not only as a
coating, but, from its more electro-positive character, it protects it
by a galvanic influence. The voltaic influence of zinc for protect-
ing iron is a subject that has occupied the attention of practical
men for a long time ; it is one of high importance : nevertheless
there seems yet a great deficiency in our knowledge of the extent
of this influence, and how and when it is effective.
Upon this subject, Professor Faraday, in the Eeport of the Har-
bors of Eefuge Commissioners, states, "Zinced iron would no doubt
resist the action of sea-water so long as the surface was covered
with zinc, or even when partially denuded of that metal : but zinc
dissolves rapidly in sea-water, and after it is gone, the iron would
follow.
"As to voltaic protection, it has often struck me that the cast-
iron piles proposed for lighthouses, or beacons,, might be protected
by zinc in the same manner as Davy proposed to protect copper by
iron; but there is no doubt the corrosion of the zinc would be rapid.
If not found too expensive, the object would be to apply the zinc
INFLUENCE OF GALVANISM IN PROTECTING. 585
protectors in a place where they could be examined often, and
replaced when rendered ineffective. In this manner I have little
doubt that iron would be protected in sea-water."
INFLUENCE OF GALVANISM IN PROTECTING METALS FROM DE-
STRUCTION BY OXIDATION AND SOLUTION. — The galvanic influence
of one metal in protecting another is in relation to their negative
and positive qualities together with their conducting powers (p.
515). Their relations in sea-water are — silver, copper, bismuth,
antimony, iron, tin, lead, cadmium, zinc; the first the most negative,
the last the most positive in the series. So that, according to this
scale, the further apart the metals may be which are selected for
experiment, the more decided will be the power of the posithe to
protect the negative. Copper and zinc operate more strongly
together than iron and zinc.
A metal that is insoluble when placed singly in a fluid, may be
made soluble by connection with a relatively negative metal placed
in the same fluid. For example, pure zinc put into muriatic acid
is unaffected, but when connected with copper in the same fluid it
is rapidly operated upon. Or a metal may be soluble in a fluid
alone, but may be rendered insoluble by connection with a relatively
positive metal which undergoes decomposition instead. Thus : cop-
per is dissolved in sea-water when alone, but when a piece of zino
is connected with it, the copper is unaffected. This last effect is
the substance of Davy's method of protection alluded to by Dr.
Faraday, in applying the principle of which it is necessary to take
into consideration,
1st, The amount and power of electricity generated by the con-
nected metals in the same fluid; and
2d, The conducting power of the metal which is being pro-
tected.
1st. The amount and power of the electricity evolved is in pro
portion to the difference of the relative negative and positive con-
dition of the metals employed. The more negative the coated metal
is, the less it requires protection, although its powers of protection
are the greatest. And the more positive the coated metal, the more
liable it is to be destroyed, and the greater the amount of electricity
required to protect it; but unfortunately it is less able to generate
this electricity when in contact with another metal. Thus these two
conditions are opposed to the application of galvanic influence for
protecting iron.
Suppose, for example, that 4 square inches of zinc, in connection
with 4 square feet of copper, give out sufficient electricity to pro-
tect the copper from sea-water, it will be found that to obtain the
same amount of electricity by iron and zinc, 2 square feet of the
latter to 4 square feet of the former are required.* Besides which,
the same quantity of electricity that protects copper will not pro-
* These proportions, given in round numbers, are nearly accurate ; but they
vary according to the kind of iron, the state ,»f the water, the distance of th*
metals, etc.
636 THE PRACTICAL METAL-WORKER'S ASSISTANT.
toct iron; nor will any quantity of zinc protect iron from corrosion
in sea- water; — even a bar of iron placed in a zinc vessel filled with
sea- water is not completely protected.
2d. The conducting power of the negative or protected metal sub-
Fig. 580. jected to submarine im
mersion is a subject of very
great importance. Suppose
a piece of copper and a
.x, & ---.„_ r~~~— — *i^ piece of zinc be connected
,„;,„;,„•„.,„., t,,,.,.-.,,,,,,,,,,.,.,,-,,,,,^ under a solution — say a
C copper bar (c) 4 feet long,
with a piece of zinc (z) 4 inches in length, erected on one end, as in
the annexed sketch:
The conducting power of the copper is so much superior to that
of the solution that the whole length of the bar will become in-
stantly negative, and the current of electricity will pass to and from
all parts of the bar at the same time in the lines b,b,b; but the cur-
rent will be more active towards the point of contact than towards
the distant extremity — the resistance of the solution being less in pro
portion to the proximity of the metals. But if a bar of iron, and a
piece of zinc as a protector, be placed in the same circumstances,
the phenomena assume quite a different aspect: the conducting
power of iron being much less than that of copper, the distant ex-
tremity will not be affected by the electric current, which will find
a more easy passage, as indicated by the dotted lines e, e, e. beyond
which the electric effort ceases; and even in that portion of the bar
which is under the influence of the current, the part nearest the
zinc is better defended than those parts which are farther dis-
tant. This partial protection, while it induces a negative state at
the near end, renders the other end more positive. Such a diver-
sity of condition gives rise to voltaic action between the two ex-
tremities of the bar, and the result is the destruction of the far
end. In all cases of voltaic protection the more equal the influ-
ence over the whole surface protected, the more perfect is the pro-
tection. An inequality of protection, such as we have described,
is productive of numerous evils. It is, we believe, the source of
many of the injuries occurring in our day to copper sheathing.
One part of a sheet becoming, by some local cause, negative, the
other parts are thus rendered positive ; the result is, that upon the
borders of an individual sheet either overlapping or underlying its
neighboring sheet, an electric current is excited, passing through
the stratum of moisture which may intervene, and the ultimate
effect is that the positive edge is dissolved as effectually as if cut
by a knife. The evil arising in one place may be so contagious as
to affect a whole neighborhood — sometimes the whole side of a
ship's bottom.
In fresh water iron cannot be protected any length of time, for
the zinc coating speedily passes into a blackish substance, which
peels off and exposes the iron to rust. When iron is simply ex-
ELECTRO -PL ATIXG. 587
posed to the air, a good coating of zinc is a sure protection. We
have seen iron of various qualities coated by the electro-processes
and exposed to the atmosphere, in all weathers, for several years,
without being more affected than a piece of zinc would be. In
spots where abrasion has taken place by accident, the protecting
power of the zinc is lost, and the iron rusts as if there were no zinc
present. No other result, however, could be anticipated, as there
can "be no electric excitation without a liquid to connect the two
metals.
The iron to be coated by zinc is to be cleaned ard prepared in
the same manner as we have described for the purpose of covering
it with copper (page 579).
CHAPTER XXX.
ELECTRO-PLATING.
THE next applications of the electro-deposition we have to
notice are those relating to silver and gold; embracing the arts of
electro- plating and gilding — arts which are gradually revolutioniz-
ing some extensive branches of manufacture, having the same
object but acting by a different means.
To MAKE SILVER SOLUTION. — The solution of silver used for
plating consists of cyanide of silver dissolved in cyanide of potas-
sium which may be prepared in various ways. We shall first de-
scribe some of the preparations most in use, and also point out
practical objections which, in special cases, have occurred under our
own observation, not omitting to specify and recommend those
methods which have approved themselves to us as being most
simple and effective.
The method generally adopted is as follows : — Metallic silver is
dissolved in four parts of nitric acid, diluted with one part of water :
the diluted acid is heated in a vessel, and the silver is added by
degrees. The operator must avoid breathing the fumes which
ascend, as they are highly deleterious. The metal being dissolved,
the solution is transferred to a large vessel, and diluted with water.
To this is added a solution of cyanide of potassium so long as a
white precipitate is formed. This precipitate is cyanide of silver;
and the action which ensues may be thus represented :
Substances used: Substances produced:
Nitrate of silver = AgO, NO5
Cyanide of potassium = KCy
Nitrate of potash = KO, NO
Cyanide of silver =AgCy
AgO, NO5 + KCy == KO, NO5 -f AgCy
The propriety of diluting the nitrate of silver before precipitat
ing by the cyanide of potassium arises from the fact, that the salts
of potash and soda (such as the nitrates, chlorides and sulphates),
588 THE PRACTICAL METAL-WORKERS ASSISTANT.
when in strong solution, dissolve small quantities of the silver salt,
and thus cause a loss, which is prevented by previous dilution with
water.
When the precipitate of cyanide of silver has settled, the clear
solution is carefully decanted, and the vessel filled up with water,
which is again decanted as soon as the precipitate has settled. This
process is to be repeated three or four times, so as effectually to
wash out the soluble salts. When properly washed, a solution of
cyanide of potassium is added to the precipitate, until it is all dis-
solved. The resulting solution constitutes the cyanide of potassium
and silver, and forms the plating solution. It ought to be filtered
previous to using, as there is always formed a black sediment, com-
posed of iron, silver, and cyanogen, which, if left in the solution,
would fall upon the surface of the article receiving the deposit, and
make it rough. The sediment, however, must not be thrown away,
as it contains silver. The cyanide of potassium, used to dissolve
the cyanide of silver, may be so diluted that the plating solution,
when formed, shall contain one ounce of silver in the gallon : of
course the proportion of silver may be larger or smaller, but that
given is what we consider best for plating.
In dissolving 100 ounces of silver, the following proportions of
each ingredient are those which we have found in practice to be the
best. Take 7 pounds of the best nitric acid* and 61 ounces of
cyanide of potassium, of the average quality described at page 576;
this quantity will precipitate the 100 ounces of silver dissolved in the
acid solution. After this is washed, take 62 ounces more of cyanide
of potassium, the solution of which will dissolve the precipitate :
this being done, the plating solution is then formed. Of course,
these proportions will vary according to the difference in the quality
of the materials; but they will serve to give an idea of the cost of
the silver solution prepared in this manner.
CYANIDE OF SILVER DISSOLVED IN YELLOW PRUSSIATE OF POT-
ASH.— We have occasionally dissolved the cyanide of silver by
yellow prussiate of potash, three pounds of which are required to
dissolve one ounce of silver. This forms an excellent plating solu-
tion, and yields a beautiful surface of silver. It must have a weak
battery power, and consequently the silver is very soft. The posi-
tive electrode does not dissolve in this solution : there is formed
upon its surface a white scaly crust, which drops off' and falls to
the bottom ; and the solution soon becomes exhausted of silver.
SOLUTION MADE WITH OXIDE or SILVER. — It has been recom-
mended to dissolve the oxide of silver in cyanide of potassium,
which forms a solution of cyanide of potassium and silver; but this
preparation is less economical, because the materials used in con-
verting the silver into an oxide are lost: it requires the same amount
* The nitric acid must be free from hydrochloric (muriatic) acid : to a small
quantity of the acid add a few drops of solution of nitrate of silver; if it gives a
white precipitate, it contains muriatic acid, and should be rejected.
ELECTRO-PLAT!^. 589
'
of cyanide of potassium as the process just described, and-^.—
moreover, an equivalent of potash into the solution, which is ;a dis-
advantage. The following diagram shows the reactions that
Substances used : tSu bstances produced :
Oxide of silver = AgO
Potash = KG
Cyanide of silver | _
and potassium j ~
Cyanide of potassium = KCy
Cyanide of potassium = KCy
AgO + 2 KCy = KO + KC, AgCy.
SOLUTION MADE WITH CHLORIDE OF SILVER. — The nitrate of
silver may also be precipitated by adding a solution of common
salt to it, and treating it in the same way as described for precipi-
tation by cyanide of potassium : this would form chloride of silver,
which may be dissolved in cyanide of potassium, thus forming the
silver solution. But the objection urged against the use of oxide
of silver is equally applicable in the case of chloride ; and much
greater care is required in precipitating large quantities and strong
solutions of silver by common salt, than by cyanide of potassium,
the chloride of silver being more soluble in the salts of the alka-
lies— as the nitrates, chlorides, and sulphates — than cyanide of
silver is ; and there is therefore great liability to loss by this
process, in which we have not the redeeming quality of a saving
of materials, as the following diagram will show :
Substances used: Substances produced:
Chloride of silver = AgCl
Cyanide of potassium = KCy
Oyanide of potassium = KCy
Chloride of potassium = KC1
Cyanide of silver )
and potassium J
C
J
AgCl + 2 KCy = KCl + KCy, AgCy.
Thus, we observe, that the action taking place is not mere solu-
tion, but decomposition ; which upon one hundred ounces of silver
in this preparation produces an impurity of seventy ounces of
chloride of potassium, which, although not very injurious to the
solution, would be much better away.
THE BEST METHOD OF MAKING SILVER SOLUTION. — The best
and cheapest method of making up the silver solution is by the
battery, which saves all expense of acids and the labor of precipi-
tation. This is effected by taking advantage of the principle of
non-transfer of metal in electrolytes (see page 561). To prepare a
silver solution which is intended to have an ounce of silver to the
gallon (see p. 588), observe the following directions : Dissolve 123
ounces of cyanide of potassium in 100 gallons of water ; get one
or two flat porous vessels, and place them in this solution to within
half an inch of the mouth, and fill them to the same height with
the solution ; in these porous vessels place small plates or sheets
of iron or copper, and connect them with the zinc terminal of a
battery : in the large solution place a sheet or sheets of silver con-
nected with the copper terminal of the battery. This arrangement
590 THE PRACTICAL METAL-WORKER'S ASSISTANT.
being made at night, and the power employed being two of Wol
laston's batteries, of five pairs of plates, the zincs 7 inches square,
it will be found in the morning that there will be dissolved from
60 to 80 ounces of silver from the sheets. The solution is now
ready for use : and by observing that the articles to be plated have
less surface than the silver plate forming the positive electrode,
for the first two days, the solution will then have the proper
quantity of silver in it. We have occasionally found a little silver
in the porous cell : it is therefore not advisable to throw away the
solution in them without first testing it for silver, which is done by
adding a little muriatic acid to it.
The amateur electrotypist may, from this description, make up
a small quantity of solution for silvering his medals or figures.
For example, a half-ounce of silver to the gallon of solution will
do very well ; a small quantity may be prepared in little more
than an hour.
As the cyanide of potassium dissolves silver without the aid
of a battery, by merely allowing a piece of silver to steep in
this solution for a few days, a plating liquor may be formed;
but this is tedious and uncertain, although for small operations,
and where porous vessels are not convenient, it will serve the
purpose.
Other solutions of silver may be employed if the law stated at
page 575 is strictly observed. Indeed, every salt of silver has not
only been tried, but is either the subject of a patent, or promi-
nently included in it. None of them, however, with the exception
of two, have we found of any practical value, besides that already
described : these are the chloride of silver dissolved in hyposul-
phite of soda, and the sulphite of silver dissolved in sulphite of
potash or sulphite of soda.
HYPOSULPHITE OF SILVER SOLUTION. — The simplest method
known to us for forming the hyposulphite of silver solution is this:
Take one pound of pure carbonate of soda, well dried, as de-
scribed at page 576 ; mix it intimately with five ounces of flour
of sulphur ; place the mixture over a slow fire without flame in a
porcelain or stoneware basin, which must be supported by an iron
trelis, or any convenient support, to prevent it touching the red
coal or flame ; keep the mixture constantly stirring, and maintain
the heat till the sulphur melts, and the mass inclines to get pasty
and rough. While in this state keep stirring for about fifteen
minutes, in order to bring every part in contact with the air. Set
the mixture to cool — after which dissolve in water. Boil the so-
lution for some time, adding sulphur; then filter it, and allow i£ to
evaporate at a slow heat. The crystals formed are hyposulphite
of soda.
To prepare the silver solution, the silver is first dissolved in
nitric acid, and then precipitated by a solution of common salt,
and washed, with the precautions stated at page 587. When the
nrecioitated chloride of silver is well washed, some of the crystals
ELECTKO-PLATIXG.
591
of hyposulphite of soda are dissolved, and the solution is added ta
the chloride of silver, which it dissolves, forming the plating solu-
tion. It is not necessary to crystallize the hyposulphite of soda,
if used as soon as made. .
The hyposulphite of silver solution is very easily decomposed
by the electric current, so that a weak battery will suffice to platu
by it: but its great objection is its liability to decompose in the
light, and to deposit the silver as sulphuret : unless great care is
exercised, the silver deposited from it will be in a granular condi-
tion, which is a great objection in plating.
SULPHITE OF SILVER PLATING SOLUTION. — The sulphite of
silver solution is prepared in the following manner, as described
by the patentee of the process :
"The solution which I use is made in the following manner: I
take of the best pearl-ash of commerce 28 Ibs (avoirdupois) and
add to it 30 Ibs (avoirdupois) of water, and boil them in an iron
vessel until the pearl-ash is dissolved ; the solution should then be
poured into an earthenware or other suitable vessel, and suffered
to stand until the liquor becomes cold. It should then be filtered,
and 14 Ibs (avoirdupois) of distilled water added thereto; sulphurous
acid gas (obtained by any of the known processes) should then be
passed into the filtered liquor until it is saturated, taking care not
to add sulphurous acid gas in excess. The liquor should be again
filtered, and the liquor so filtered is what I term the solvent, or
sulphite of potash.
"To make the silvering liquor which I use in coating with silver
the surface of articles formed of metal or
metallic alloys, I dissolve 12 oz. (avoir-
dupois) of crystallized nitrate of silver
in 3 Ibs. of distilled water (in a clean
xearthenware vessel), and add to the solu-
tion, by a little at a time, the before-
mentioned solvent, so long as a whitish
colored precipitate is produced (care
being taken not to add more of the
solvent than is necessary). After the
precipitate has subsided, I pour oft' the
supernatant liquor, and wash the pre-
cipitate with distilled water. To the
precipitate I add as much of the before-
mentioned solvent as will dissolve it,
and afterwards add about Jth part more
of the solvent, so that the solvent may
be in excess; I then stir them well together and let them remain
about 24 hours, and then filter the solution, when it will be ready
for use. This is what I designate silvering liquor."*
Sulphurous acid gas for making the above liquor may be p re-
Fig. 581.
,- —
* Repertory of Patent Inventions, 5tli series, p. 210, 1843.
692 THE PRACTICAL METAL- WORKER'S ASSISTANT.
pared by heating sulphuric acid, undiluted, in a flask or any con-
venient vessel, to which should be added small pieces of copper or
charcoal: the gas escaping is made to pass into the solution to be
saturated with it.
Fig. 581 is a very convenient apparatus for the preparation of
this gas for saturating solutions.
This solution is also very easily decomposed by the electric cur-
rent, and serves the purposes of plating very well ; but it is also
liable to decomposition by light, and is not so good in practice as
the solution of cyanide of potassium and silver. The latter solu-
tion is, however, liable to a kind of decomposition not yet fully
investigated, but it is wholly confined to its impurities, and it never
deposits its silver ; whereas the decomposition that takes place in
the sulphite or hyposulphite affects the silver compound, and pre-
cipitates the silver from solution.
To EECOVER SILVER FROM SOLUTION. — When a silver solution
gets out of order, and cannot be rendered fit for use again, the
silver may be recovered by adding to the solution any acid that
will neutralize the alkali ; if nitric or sulphuric acid be used, the
silver precipitates as cyanide, but if hydrochloric acid be used, the
silver will be precipitated as a chloride : in either case the solution
should be diluted, or a portion of the precipitate will be re-dissolved.
The precipitate is allowed to deposit, the clear liquor decanted, and
the vessel filled with water to wash the precipitate, which is after-
wards collected upon a filter and dried, and then mixed with twice
its weight of carbonate of potash, and fused in a Hessian crucible
for 15 minutes, or until the fused fluid ceases to effervesce. On
removing the crucible, and pouring the whole into an iron ladle,
when cool the silver will be found in the metallic state at the bot-
tom of the ladle.
In these operations when pouring the acid into the cyanide
solution, great care must be taken not to inhale the fumes given
off, which are very abundant, sickening, and poisonous. The
operation should be done in the open air, and even then it is bad.
Instead of throwing down the silver by an acid it is better to evap-
orate the solution to dryness, and to fuse the product as described;
in which case the cyanide is an excellent reducing flux, requiring
no addition of carbonate of potash, and saves the necessity of evolv-
ing poisonous fumes.
When the solution has contained yellow prussiate of potash, it
is found that during this fusion portions of the metal sometimes
form a scoriaceous nodule at the bottom of the crucible, and all the
heat that can be applied by an ordinary assay furnace will not fuse
it. This refractory piece, when cooled, has generally a rough
scoriaceous surface, and is exceedingly hard. When filed it has more
the color of German silver than of real silver; it has considerable
malleability, and retains its bright appearance 'for a long time wit1 -
out tarnish. An analysis of this alloy gave —
ELECTRO-PLATING. 593
Silver 82-15
Copper 9-12
Iron 7'50
Carbonaceous matter . . '46
99-23
If we suppose the carbonaceous matter to be an accidental im-
purity, this alloy will nearly agree with the formula Ag3 Cu Fe.
PREPARATION OF ARTICLES FOR PLATING. — Articles that are to
be plated are first boiled in an alkaline ley, to free them from
grease, then washed from the ley, and dipped into dilute nitric
acid, which removes any oxide that may be formed upon the sur-
face; they are afterwards brushed over with a hard brush and sand,
of which a kind obtained from the Isle of Wight, and known as
silver-sand is best. The alkaline ley should be in a caustic state,
which is easily effected by boiling the carbonated alkali with slaked
lime, until, on the addition of a little acid to a small drop of the solu-
tion, no effervescence occurs. The lime is then allowed to settle, and
the clear liquor is fit for use. The ley should have about half-a-
pound of soda-ash, or pearl ash, to the gallon of water. The nitric
acid, into which the article is dipped, may be diluted to such an
extent that it will merely act upon the metal. Any old acid will
do for this purpose. In large factories the acid used for dipping
before plating is generally afterwards employed for the above pur-
pose of cleaning.
The article being thoroughly cleaned and dried, has a copper
wire attached to it, either by twisting it round the article or putting
it through any open part of it, to maintain it in suspension. It is
then dipped into nitric acid as quickly as possible, and washed
through water, and then immersed in the silver solution, suspend-
ing it by the wire which crosses the mouth of the vessel from the zinc
of the battery. The nitric acid generally used and found best for
dipping has a specific gravity 1*518, contains 10 per cent, sulphuric
acid, and is got at about 6 cts. per Ib. The article is instantaneously
coated with silver, and ought to be taken out after a few seconds
and well brushed. On a large scale, brushes of brass wire attached
to a lath are used for this purpose; but a hard hair brush with a
little fine sand will do for small work. This brushing is used iu
case any particle of foreign matter may be still on the surface. It
is then replaced in the solution, and in the course of a few hours a
coating of the thickness of tissue-paper is deposited on it, having
the beautiful matted appearance of dead silver. If it is desired to
preserve the surface in this condition, the article must be taken
out, care being taken not to touch it by the hand, and immersed in
boiling distilled water for a few minutes. On being withdrawn,
sufficient heat has been imparted to the metal to dry it instantly. If
it is a medal, it ought to be put in an air-tight frame immediately,
or if a figure, it may be at once placed under a glass shade, as a
38
594 THE PRACTICAL METAL-WORKER'S ASSISTANT.
very few days exposure to the air tarnishes it, by the formation of
sulphuret of silver, and that more especially in a room where there
is fire or gas. If the article is not wanted to have a dead surface,
it is brushed with a wire brush, and old ale, beer, or water contain-
ing in solution a little gum, glue, or sugar, but the amateur may use
a hard hair brush. It may be afterwards burnished according to
the usual method of burnishing, by rubbing the surface with con-
siderable pressure with polished steel or the mineral termed blood
stone.
We may remark, that in depositing silver from the solution, a
weak battery may be used ; though when the battery is weak the
silver deposited is soft, but if used as strong as the solution will
allow/say 8 or 9 pairs, the silver will be equal in hardness to rolled
or hammered silver. If the battery is stronger than the solution
will stand, or the article very small compared to the size of the
plate of silver forming the positive electrode, the silver will be de-
posited as a powder. The average cost of depositing silver in this
way is 4 cts. per ounce. Gas should never be seen escaping from
either pole: and the surface of the article should always correspond
as nearly as possible with that of the positive electrode, otherwise
the deposit runs the risk of not being good ; it requires more care,
and the solution is apt to be altered in strength, because if the
positive electrode be large compared with the negative, the solu-
tion will become stronger in silver, while if smaller in proportion
the solution will become exhausted of silver.
In plating large articles (such as those plated in factories), it is
not always sufficient to dip them in nitric acid; wash and immerse
them in the solution, in order to effect a perfect adhesion of the
two metals. To secure this, a small portion of quicksilver is dis-
solved in nitric acid, and a little of this solution is added to water,
in sufficient quantity to enable it to give a white silvery tint to a
piece of copper when dipped into it: the article then, whether made
of copper, brass, or German silver, is, after being dipped in the
nitric acid and washed, dipped into the nitrate of mercury solution
till the surface is white : it is then well washed by plunging it into
two separate vessels containing clean water, and finally put into
the plating solution. This secures perfect adhesion of the metals.
One ounce of quicksilver thus dissolved will do for a long time,
though the liquor is used every day. When the mercury in this
solution is exhausted, it is liable to turn the article black upon
being dipped into it: this must be avoided, as in that case it also
causes the deposited metal to strip off.
PRACTICAL INSTRUCTIONS IN PLATING. — We need hardly add
that it is necessary that the battery should be so arranged, that the
quantity of electricity generated should correspond with the sur-
face of the articles to be coated, and that the intensity should bear
reference to the state of the solutions; that is to say, that the
quantity should be sufficient to give the required coating of metal
in a given time, and the intensity such as to cause the electricity to
ELECTRO-PLATING.
595
pass through the solution to the articles. It is also essential for
regular working, as stated above, that the plates of metal forming
the positive pole in the solution should be of corresponding sur-
face to the articles to be coated, and face them on both sides.
The following is the arrangement adopted in some of the large
plating manufactories : — The vat, or plating vessel measures about
6 J feet in length, by 33 inches in breadth, and 33 inches in depth,
and generally contains from 200 to 250 gallons of solution; the
silver plates serving as electrodes, which were formerly nailed
upon frames of wood, are now generally fixed upon light iron
frames, these not being affected by the solution: two battery
troughs are arranged as seen in Fig. 582, consisting of 6 batteries
of three pairs intensity. The zinc plates immersed in the acid
measure 6 inches by 7 inches, the exposed surfaces of which
measure 84 square inches : these multiplied by 6 give 504 square
inches, from which electricity is disengaged. The surface of the
silver electrodes exposed to the articles receiving the deposit vary
from 3000 to 4000 square inches of surface.
The following figure, with explanation, will illustrate these ob-
servations :
Fig. 582,
A,Yat or vessel containing the solution; B, Battery with zinc pole
z, connected with rods R R; and copper pole c, connected with the
metallic sheets P P, in the solution, by means of the copper slip r :
D D, are articles suspended in the solution by wires from the rods
R R; s, the solution. So soon as the articles, which are connected
with the negative pole of the battery, and the metallic sheets, con
596 THE PRACTICAL METAL-WORKER'S ASSISTANT.
nected with the positive pole, are both immersed in the solution,
the galvanic circuit is completed.
In most plating establishments the batteries are now placed out-
side the house, and the connecting rods are brought from them into
the vats, so as to preserve the workmen from the injury arising
from inhaling the hydrogen gas which is given off' by the zincs, as
it often contains arsenic, and hence is highly injurious to health ;
the gas of the battery has a strong effect upon the nostril, exciting
dryness with pain. Wherever the batteries are placed, they should
not be exposed to cold, as their operation is much affected by the
temperature.
In the early days of electro-plating the batteries used were round.
They consisted of a copper cylindrical vessel, about 20 inches deep,
and 5 inches diameter, filled with dilute sulphuric acid. A piece of
wood was placed at the bottom of this vessel, and a cylinder of zinc,
the same depth as the copper vessel, and about 3 inches diameter,
was placed inside the copper vessel. A wooden ring, floating on
the surface of the acid, prevented the zinc and copper touching — a
binding screw was attached to each, and formed a battery of a single
pair. Six batteries of this size were connected with such a vat as is
described above. The test of strength employed to determine
whether the working power was sufficient, was that, when connected
with an electro-magnet, it should support a 7 Ib. weight. We be-
lieve that many platers and gilders still use such batteries, and that,
when the solutions and apparatus are all in good condition, they do
well. They are, however, far from being so economical as the bat-
tery with square plates shown above. Some electro -metallurgists
use large and deep stoneware vessels in which are placed the zinc
and copper — the plates having several square feet of surface. We
have already shown, when treating of batteries, that very large
plates are not consistent with economy.
To ascertain the amount of metal deposited, it is only necessary
to weigh the articles carefully before and after plating. But be-
tween the first weighing and the immersion of the articles in the
plating solution there is the dipping into nitric acid to be ac-
counted for : this, on an average, will cause a loss of about one
pennyweight upon an article of the size of a foot square; thus, if a
waiter of a foot square, made of copper or German silver, shows,
when coated, a difference in weight of 19 pennyweights, the silver
laid on must be estimated at an ounce, or 20 pennyweights. When
the article is a " replate," i. e., an old plated article that has become
bare of silver in parts, the allowance or reduction for the dipping in
the acid is only to include the portions left bare, for the silvered
parts are not acted upon by it. One of the practical difficulties
which the inexperienced will occasionally meet with when a " re-
plate" is dipped in the nitric acid, is, that a galvanic action is pro-
duced between the silver and the copper portions, which causes a
black line round the edge of the silver: this ought immediately to
be rubbed o&, but even with rapid and careful rubbing there is
ELECTRO-PLATING. 597
great danger that the coating will loosen and blister at those parts ;
and beside this, it happens that the parts of the " replate" which.
are sound, the silver not being acted upon by the acid, but rather
protected by the galvanic action, are not in a fit state to receive and
maintain a perfect adhesion of the deposit, and therefore the risk is
great that the new coating will separate from the old, or, in technical
language, that the part will strip. Under these circumstances
experience has taught that the best way to proceed is to take all
the old silver off the article, and deposit an entirely new coating.
There are two methods of taking off the silver :
TAKING SILVER FROM COPPER, ETC. — First, stripping or dissolving
it off; this is done by putting into a stoneware or copper pan some
strong sulphuric acid' (vitriol), to which a little nitrate of potash is
added : the article is laid into this solution, which will dissolve the
silver without materially affecting the copper ; saltpetre is added
by degrees, as occasion requires ; and if the action is slow a little
heat is applied to the vessel. The silver being removed, the article
is washed well and then passed through the potash solution, and
finished for plating. When the sulphuric acid becomes saturated
with silver it is diluted, and the silver is precipitated by a solution
of common salt : the chloride of silver formed is collected and fused
in a crucible with carbonate of potash, when the silver is obtained
in a metallic state, as a knob or button. The crucible should not
be over two-thirds full and should be kept in fusion till effervescence
ceases. The crucible is then removed from the fire, and, when cool,
it is broken.
The article thus stripped by acids often shows a little roughness,
not from the effects of the acid, but because the copper under the
silver has not been polished ; it is therefore a necessary practice in
the electro-plating factories to polish the articles before plating.
This is done by means of a circular brush, more or less hard as re-
quired, fixed upon a lath, and a thin paste made of oil and pumice-
stone ground as fine as flour. By this process the surface of any
article can be smoothened and polished ; but a little experience is
required to ensure success, and enable the operator to polish the
surface equally without leaving brush marks. We need scarcely
say, that after this process the article must be cleaned in potash
before it is plated.
Second Method. — Instead of stripping off the silver by means of
acid, it is a more common and preferable mode to brush off the
silver by the operation just described. In this case the brushings
must be collected, dried, and burned ; this may be done in an iron
pan, keeping it at a red heat until all carbonaceous matters are
consumed, the remainder is fused with carbonate of soda or potash,
when the silver is obtained, in combination with a little copper.
CYANIDE OF SILVER AND POTASSIUM, ITS DECOMPOSITION DUR-
ING THE PLATING PROCESS. — The silver salt in the plating solution
is a true double salt, being, as already described, a compound of
one equivalent of cyanide of silver, and one of cyanide of potassium
598
THE PRACTICAL METAL-WORKER S ASSISTANT.
Fig. 583.
— two distinct salts. In the decomposition of the silver solution
by the electric current, the former, cyanide of silver, is alone
affected: the silver is deposited, and the cyanogen passes to the
positive plate or electrode. The cyanide of potassium is therefore
set at liberty upon the surface of the article receiving the silver
deposition, and its solution being specifically lighter than the gen-
eral mass of the plating solution, rises to the top : this causes a
current to take place along the face of the article being plated. If
the article has a flat surface, suppose that of a waiter or tray, upon
which a prominence exists, as a mounting round the edge, such as
a gadroon, see Fig. 583, it will cause lines and ridges from the bot-
tom to the top, as already described at page
561. Newly -formed solutions are most sub-
ject to produce this annoyance.
OTHER EFFECTS PRODUCED IN WORKING.
— As the cyanogen combines with the silver
plate forming the positive electrode, it is dis-
solved by the free cyanide of potassium,
which the solution must have; and, being
specifically heavier, sinks to the bottom, by
which a current downwards is excited: this
is of no greater annoyance than that it ren-
ders the solution of unequal density, which
in its turn yields an unequal deposit, more
being laid upon the lower parts of the
article than on the upper: the silver plate
also is destroyed more rapidly at the bottom
than at the top. except at the surface of the
solution, if the silver be above it, where the
plate gets cut through. In a new solution,
which contained 1 J ounces of silver to the gallon, we have found,
just before taking out the articles, that the top part of the solution con-
tained 200 grains of silver less, and the bottom part 200 grains more
per gallon, than when the articles were put into it. These difficulties
and annoyances may, however, be nearly surmounted by keeping the
articles in motion: agitating or stirring the solution occasionally
would also obviate these annoyances; but this is not advisable, fur
if the sediment (which always forms) were stirred up it Would settle
upon the face of the articles and make them rough. Where there is
engine power it is an easy matter to keep the articles in motion ;
but where this power is not available, a very simple apparatus, in-
vented by Mr. Alexander Mitchell, of Glasgow, may be fitted up at
a trifling cost, to give the necessary motion by clockwork. The
annexed sketch exhibits this apparatus.
MACHINE FOR MOVING GOODS WHILE SUBJECTING TO THE ELEC-
TRO-PLATING PROCESS. — Fig. 584, side elevation, with front frame
off; Fig. 585, end elevation of that part of front frame where the
fly is luld ; Figs. 586 and 587, the plating vat, with frame moving
on inclined plane.
ELECTRO-PLATING.
599
The large wheel A, Fig. 585, is propelled by a weight suspended
from the roof by a cord which winds round its barrel, the same as
common clockwork. The circumference is studded with small pins
which catch the arm B, moving it in a downward direction, and
consequently moving the arm c in a forward direction. The latter,
being attached to the frame by a small rod R, Figs. 585 and 587,
moves it up the inclined plane E, Fig. 587, until the pin fixed in
the wheel A passes the end of the arm B. The frame then moving
down the incline E, brings B in gear with the next pin, and the
same motion again takes place, and so on successively. The speed
Figs. 584
585.
is regulated by the train moving in an endless screw fitted on the
last wheel of the arbor of a fan. The four holes in Fig. 585 are
for bolts or pillows for screwing the two frames together. The
frame has four pulleys and inclines, the latter adjustable to a
greater or less degree by the screw and grove at E*
DEPOSIT DISSOLVING OFF IN SOLUTION. — In depositing any
metal, but more particularly such as require solutions having an
excess of the solvent, such as of cyanide of potassium in the de-
positing of gold and silver, care should be taken that nothing stops
600
THE PRACTICAL METAL-WORKER'S ASSISTANT.
the current of electricity suddenly, while the article being deposited
upon remains in the solution, otherwise the metal deposited will
speedily dissolve off. This we have often experienced, and many
others have no doubt done the same. Indeed, we have seen a
beautiful deposit going on, and left the operation with great hope
of excellent results, but on returning shortly after have found the
whole dissolved off. And often, when the process was apparently
going on well, and the articles had been in the solution the usual
time to receive a fair coating of metal, upon taking them out and
weighing them there was hardly any perceptible difference from
the original weight — in short, there had been no material deposit.
These phenomena will be found to occur with the greatest fre
quency when the solutions and the batteries are in the best con-
dition for working, and when the article upon which the deposit
is going on,. and the pole or plate of metal forming the positive
Fig. 586,
TROUGH OR VAT
Fig. 587.
((5)7
VAt
electrode are at a considerable distance from each other. But be-
fore explaining what we consider to be the cause of these an-
noyances we will refer to another phenomenon connected with
them.
OPPOSITE CURRENTS OF ELECTRICITY FROM VATS. — If, under
the circumstances referred to, and when the deposit has gone on for
some time, the wires connecting the battery with the electrodes in
the depositing solution be disconnected from the battery, and their
two ends be joined together, a current of electricity nearly as
strong as that from the battery will pass through the wires, but
in the opposite direction from that which was obtained by the bat-
tery ; and ii two pieces of metal were attached to these wires and
put into a solution of copper, or any metal, a deposition would
ELECTRO-PLATING. 601
occur, the. original electrodes now constituting a battery in relation
to this second decomposition cell : the current, however, would
gradually weaken until it ceased. The cause of all these actions
and reactions is this : The article being plated with silver in con-
nection with the battery, exhausts the solution of silver around it,
leaving free cyanide of potassium in solution, while around the
sheet of silver which is serving as the positive electrode, the solu-
tion is on the contrary becoming saturated with silver, so that we
have all the conditions necessary to constitute a battery, having
silver in two kinds of solution — the one capable of dissolving
silver, the other not. In these conditions lies the source of the
annoyances described above. From the moment the deposition of
metal begins, there also arises an opposite current of electricity,
tending to neutralize the effects of the battery, which current goes
on increasing in quantity until the two currents neutralize each
other, or it may be until the current from the trough overpowers
that from the battery. In the latter case, as we have said, there
may, at the termination of the ordinary period, be little or no
silver deposited on the articles intended to be plated. Motion in
the silver or depositing solution will prevent all these annoy-
ances ; and this being now generally adopted, these phenomena are
not now observed, but the effects take place less or more in every
solution.
TEST FOR THE QUANTITY OF FREE CYANIDE OF POTASSIUM IN
SOLUTIONS. — It has been already mentioned that the cyanide of
silver, as it forms upon the surface of the silver plate, is dissolved
by the cyanide of potassium. This renders it necessary to have
always in the solution free cyanide of potassium. Were we to
use the pure crystalline salt of cyanide of potassium and silver,
dissolved in water, without any free cyanide of
potassium, we should not obtain a deposit be- Fig- 588-
yond a momentary blush; as the silver plate or
electrode would get an instantaneous coating of
cyanide of silver, and this not being dissolved
the current would stop. The quantity of free
cyanide of potassium required in the solution
varies according to the amount of silver that is
present, and the rapidity of the deposition. If
there be too little of it, the deposit will go on
slowly ; if there be too much, the silver plate
will be dissolved in greater proportion than the
quantity deposited, and the solution will conse-
quently get stronger. The proportion we have
found best is about half by weight of free cyanide
of potassium to the quantity of silver in solution ;
thus, if the solution contains two ounces of silver
to the gallon, it should have one ounce of free
cyanide of potassium per gallon. This is known
by taking some nitrate of silver, dissolving it in distilled water
602
and placing it in a common alkalimeter, graduated into 100 parts,
Fig. 588. The proportion of the nitrate of silver in the solution is
that every two graduations of the solution should contain 1 grain.
A given quantity of the plating solution is now taken — say 1 ounce
by measure, and the test solution of nitrate of silver is added to it
by degrees, so long as the precipitate formed is redissolved. When
this ceases the number of graduations is then noted, and the follow-
ing equation gives the quantity of free cyanide. Every 175 nitrate
of silver are equal to 130 cyanide of potassium in solution. Sup-
pose 20 graduations were taken, equal to 10 grains nitrate of silver,
then 175: 130 : : 10 : 7.4 grains free cyanide of potassium. This,
multiplied by 160, the number of fluid ounces per gallon, will make
about 2J ounces. We have taken 2 graduations to one grain of
nitrate of silver, that the solution may be considerably dilute and
less liable to error. The following table is calculated at a half
grain nitrate of silver to the graduation, and will be a guide to the
student or workman. The quantity of solution tested is one ounce
by measure.
Number of Free cyanide per gallon,
graduations used. oz. dwt. gr.
1 0 2 13
2 0 5 3
3 0 7 16
4 0 10 6
5 0 12 19
6 0 15 9
7 0 17 22
8 1 0 13
9 1 3 1
10- 1 5 12
11 1 8 5
12 1 10 19
13 1 13 8
14 1 15 22
15 1 18 11
16 2 1 2
17 2 3 14
18 2 6 2
.19 2 8 11
20 2 11 0
Another method may be adopted. If, for instance, we dissolve
a small quantity of sulphate of copper and add to it an excess of
ammonia, there, is produced a deep blue color. Cyanide of po-
tassium will destroy the blue color, in a fixed chemical proportion.
To obtain this proportion, take ten grains of pure cyanide of po-
tassium and dissolve in water ; then take a certain quantity, say
100 grains, of sulphate of copper and convert it into ammoniuret,
the whole measuring a given quantity, and pour from an alkalime
ELECTRO-PLATING. 603
ler this blue liquor into the cyanide of potassium till it ceases to
destroy the color, then mark the number of graduations required,
and that amount of copper solution will represent 10 grains cyanide
of potassium — a quantitative test will thus be got for the full cyan-
ide of potassium in the solution, and should be used as follows :
Say that the color of 60 graduations of the blue solutioa was de-
stroyed by the 10 grains of cyanide of potassium, then to test the
quantity of free cyanide of potassium iii the plating solution, take
60 graduations of the blue liquor in any convenient vessel, and
add to it from an alkalirneter the plating solution till the color of
the blue liquor is destroyed, then note the quantity which contains
10 grains free cyanide, from which the quantity in the whole
solution may be calculated.
KATE OF DEPOSITING SILVER. — When articles are taken out of
the solution they are swilled in water, and then put into boiling
water. They are afterwards put into hot sawdust, which dries
them perfectly. Their color is chalk- white. They are generally
weighed before being scratch-brushed ; that is, brushed with the
fine wire brushes and stale beer as already described. Although
this operation does not displace any of the silver, still, in taking
off the chalky appearance, there is a slight loss of weight. The
appearance after scratching is that of bright metallic silver. Any
thickness of silver may be given to a plate by continuing the
operation a proper length of time. One ounce and a quarter to one
ounce and a half of silver to the square foot of surface, will give
an excellent plate about the thickness of ordinary writing paper.
BRIGHT DEPOSIT. — A little sulphuret of carbon added to the
plating solution prevents the chalky appearance, and gives the
deposit the appearance of metallic silver; the reaction which takes
place in this mixture is not yet understood. The best method of
applying the sulphuret of carbon is to put one or two ounces into
a large bottle, then fill it with strong silver solution, having an
excess of cyanide of potassium, and let it repose for several days,
shaking it occasionally. A little of this silver solution is added,
as required, to this plating solution, which will give the articles
plated the same appearance as if scratched. It is also found that
the presence of sulphuret of carbon prevents the solution from
going out of order ; indeed we have seen a solution that has been
constantly working from two to three years, while, generally, they
were subject to go out of order for a time, in less than one year —
although, after standing a time, they would recover — but these arc
curious reactions not yet investigated.
DIFFERENT METALS FOR PLATING. — Silver may be deposited
upon any metal, but not upon all with equal facility. Copper,
brass, and German silver, are the best metals to plate ; iron, zinc,
tin, pewter, and Britannia metal, are much more difficult ; lead is
easier, but it is not a good metal, because of the rapidity with which
it tarnishes, and, from its softness, easily yields to the pressure of
the burnisher : nevertheless all these metals and alloys may be,
604 THE PRACTICAL METAL-WORKER'S ASSISTANT.
and are, plated, hut cannot give the satisfaction which brass, cop-
per, or German silver afford. In plating upon alloys having tin
in them, such as Britannia metal, they must not be dipped into
nitric acid previous to plating ; but into a hot and strong solution
of caustic potash or soda for five minutes, and put directly into the
plating solution (which should have an excess of cyanide of potas-
sium, and the battery be as strong as the liquor will admit of with
out gas being evolved), until covered, when the silver may be
thickened by an ordinary solution and battery.
ELECTRICITY GIVEN OFF FROM SANDY DEPOSITS.— We may
mention that when depositing silver upon a large surface, and the
solution or battery being in the condition to give the sandy deposit,
or rather when the deposit has gone on for a long time and the
solution not been agitated, so that it has become very much
exhausted of silver round the article, the deposit towards the end
of the time has been almost impalpable to the touch, like flour :
sometimes the grains were a little coarser. The practice, in such
cases, is to lift the articles from the solution, and to place them in
boiling water, and after steeping there some time, to take them out,
when the heat of the metal soon causes it to dry. Under these
circumstances, when the deposit was of the sort stated, we have
seen on a large waiter or tray, when the hand was rapidly drawn
over the surface, after it was dried in the manner described, the
same effect produced as when the hand is drawn over an electrified
handkerchief, or sheet of paper, accompanied with a crackling
noise and pricking sensation. We have repeatedly observed these
phenomena, but never having chanced to be in the dark, no light
was visible from the surface rubbed. Although these are the con-
ditions under which the observations were made, the phenomena
were not produced every time these conditions were found. It is
probably caused by the fact that this kind of deposit, which is of a
chalky appearance, is a bad conductor of electricity, and as the
boiling water was often very impure, holding salts in solution, the
rapid evaporation of the water from the surface of this sort of
deposit might leave it excited for a short time, and the hand being
drawn across at the time of excitation, the electricity was liberated.
THE OLD METHOD OF PLATING. — Many objections have been
urged against the application of electro-deposition to the purposes
of plating, as a branch of manufacture, either as a competitor or
substitute for the old method, technically called Sheffield plate — so
called because Sheffield is a principal seat of that manufacture.
To enable our readers to form a proper estimate of the objections
urged, by enabling them to judge of the relative importance and
value of the two processes, we shall add a brief description of the
old method.
An ingot of copper being cast, was filed square and smooth,
and a piece of silver was placed upon it, the two surfaces being
perfectly clean: a little borax having been introduced between the
two metals, they were bound together with iron wire, and then
ELECTRO-PLATING. 605
neated in a furnace nearly to the melting point ; the small quan-
tity of borax increased the fusibility of the two metals at their
surface, and thus they were fused together. When fusion was
effected the metals were subjected to the dilating process of heavy
rollers, the dimensions in length and width being regulated accord-
ing to the articles to be made. This sheet formed the base or
foundation of every article, of whatever shape or form, and how-
ever it was to be ornamented when finished.
To produce ornaments, leaf silver was stamped in iron dies
representing the ornaments required, which, when removed from
the dies, were filled with an alloy of lead and tin. These were
then soldered upon the flat or shaped plain surface with soft
solder, which melts at a very low temperature : thus were pro-
duced the silver edges, or mounts.
The quality of the ornament depended entirely upon the price
of the article ; but whatever the quality, all ornaments in the old
mode of plating were thus made, the only difference being the
thickness of the silver leaf used : — Ornamental feet, handles, knobs,
etc., were made in the same manner, being struck up in two parts,
filled with lead and tin, soldered together with soft solder, and
afterwards soldered to the main body. Articles (such as table
candlesticks) which would be too heavy if filled with lead, were
filled with rosin, pitch or any other similar substance, for the pur-
pose of preventing the article being flattened by pressure. Hence
it is evident that no solid article could be made by the old mode of
plating, the only way of producing articles being to work them up
by the hammer, or to strike them in dies from a flat surface : and
being restricted to the use of soft solder, on account of the plated
metal and the shells of silver, forming the edges, not supporting
the required heat to melt silver solder, it is equally evident that
the joinings so constructed would be easily removed either by
force or heat.
The nearest approach to solid articles made by the old method
of plating, were forks and spoons : these were generally made of
iron, thin silver being soldered upon the surface, which was after-
wards dressed smooth, and polished.
The heat used in this operation was merely that of an ordinary
soldering iron; because, were a greater heat applied, the silver
would form an alloy with the tin and lead of the solder, and melt :
the same heat that cemented the metals in the first instance would
be sufficient to disunite them ; and thus, when these forks were
exposed in hot gravy, the solder was liable to become soft, and
the silver covering, yielding readily to the knife, to peel up or
become abraided, in consequence of the soft intervening metal.
ADVANTAGES OF ELECTRO-PLATING. — The advantages offered
to the plater by the electro-process are many, arising from the fact
of the articles being plated after, instead of before, being manufac-
tured. This at once entirely removed all those restrictions on
taste and design, under which the plater was forced, by the nature
of his process, to labor.
606 THE PRACTICAL METAL-WORKER'S ASSISTANT.
The following may be considered some of the principal differ-
ences existing in the two processes of plating — the old method
and the electro-process :
1. The electro-plater is not limited in the use of the metal upon
which he plates. There is generally used, as the basis of all elec-
tro-plated goods, a hard white metal, which possesses the sound,
and approaches very nearly to the color, of silver. Inferior goods
are sometimes made in brass.
2. The electro-plater is not restricted to the use of soft solder,
which melts at a very low temperature, and forms a very insufficient
joint, besides preventing any sound or ring in the article so soldered.
Where cheap goods are required, this may be used in this process
as well as in the old, but is always open to the same objection.
All goods of superior quality, made for the electro-process, are
soldered with what is termed in the trade hard silver solder, com-
posed of 2 parts of silver and 1 part of brass melted together,
which is not affected by any ordinary degree of heat, and presents
a joint as strong as the metal itself.
The common .solder of braziers may also be used with advan-
tage : it is very hard and durable and requires a strong heat to
melt it.
3. The electro-plater, in producing ornamental articles, is not
obliged to incur the expense of cutting iron dies for every minute
portion ; being under no restriction, he models his pattern, and by
casting and chasing in solid metal, produces an exact copy, which
is afterwards plated or gilt.
Thus any pattern which can be executed in silver may be readily
made in plate by this method.
4. The junction of the plating with the metal below, by the
electro-process, is perfect, without the presence of any intervening
substance : the forks and spoons thus made are not open to the
objection of the old process, and are found to answer all the pur-
poses of silver, in sound, appearance, and wear : they are generally
tested, previously to polishing, by exposure in a furnace to a red heat.
5. From the facility with which old goods may be now restored,
these goods bear an intrinsic value ; whereas before the introduc-
tion of the electro-process, a plated article worn through in any
part was valueless.
OBJECTIONS TO ELECTRO-PLATING. — Several objections to the
electro-process have been keenly urged ; but they may all be re-
duced to the following :
1st objection : Deposited metal is crystalline, and therefore,
though it may impart in appearance a silver coating, it must neces-
sarily be full of minute interstices between the crystals : hence
when a metal, such as copper, is plated, it is liable to be acted upon
by the atmosphere, or injured by whatever is brought into contact
with it
This objection was not without foundation, as all deposited
metals are crystalline in texture, but they do not necessarily leave
ELECTRO-PLATING. 607
interstices ; the objection, however, is almost entirely removed by
keeping the articles in motion during the deposition : by motion
and proper arrangement of battery we have deposited silver of as
high specific gravity as hammered silver, which could not be the
case if it were porous.
2d objection : As only pure silver is deposited, it must necessarily
be soft, and consequently liable to abrasion, and more rapid wear.
This objection is also partly true. Only pure silver can be
deposited; but it is not necessarily soft: the quality of the deposit,
in this respect, depends (as already noticed) a great deal upon the
nature of the solution and the battery power. Intensity of battery
gives hardness to the metal deposited. There is no complaint
more common amongst the burnishers of electro-plated articles,
than that the metal is hard ; and it is far from being an uncommon
occurrence, that some goods have to be heated so that they may be
more easily burnished or polished. How far this annealing may
affect the wear of the goods is not yet ascertained. That the silver
is pure we think an advantage — hence* the superior color which
electro-plated goods possess : besides which, purchasers are not
subject to the risk of having a plate much alloyed.
3d objection: The mounts or prominences of articles, which
must have the greatest wear, have the least and thinnest deposit.
This objection is entirely without foundation, as the prominences
have always the greatest portion of deposit, and the hollow parts
the least.
SOLID SILVER ARTICLES MADE BY THE BATTERY. — Silver may
be deposited from its cyanide solution upon wax moulds polished
with black lead, almost as easily as copper ; but for this purpose
it is better to have the solution much stronger in silver than for
plating. We have found that 8 ounces of silver to the gallon of
solution make a very good strength. Nevertheless, no articles are
made in, silver by depositing upon wax in this manner. Strong
solutions of cyanide of potassium and silver act upon wax, and
would soon destroy a mould. The method of making articles in
solid silver by the electro-process has been already explained (page
5-i4,) namely, a copper mould is made by the electrotype, and the
silver is deposited within this mould to the proper thickness ; after
which it is kept in a hot solution of crocus and muriatic acid, or
boiled in dilute hydrochloric acid, which dissolves the copper with
oat injuring the silver.
The method which we esteem as best for dissolving off the cop
per is this : an iron solution is first made by dissolving a quantity
of copperas in water, placing it on a fire till it begins to boil : a
little nitric acid is then added — nitrates of potash and soda will do
just as well — the iron, which is thus peroxidized, may be precipi
tated either by ammonia, or carbonate of soda; the precipitate
being washed, muriatic acid is added till the oxide of iron is dis
solved. This forms the solution for dissolving the copper. When
the solution becomes almost colorless, and has ceased to act on the
608 THE PKACTICAL METAL-WORKER'S ASSISTANT.
copper, the addition of a little ammonia will precipitate the iron
again; after a little exposure, the copper remains in solution, which
is decanted off and preserved for recovering the copper ; this is
done by neutralizing the ammonia by an acid, and putting in pieces
of iron, which deposit the copper in the metallic state. The pre-
cipitate of iron is again dissolved in muriatic acid, and employed
in dissolving the copper. Thus the iron may be used over and
over again with little trouble, and the persalt of iron will be found
to dissolve the copper more rapidly than an acid ; persulphate of
iron must not be used, as it dissolves the silver along with the cop
per. The silver article is then cleaned in the usual way (page 593),
and heated to redness over a clear charcoal fire, which gives it the
appearance of dead silver, in which state it may be kept, or, if
desired, it may be scratched and burnished.
When ammonia is first added to the above solution of copper
and iron, both these metals are precipitated together as a brown
precipitate. After a little exposure, the copper dissolves, and the
iron is at the same time peroxidized, having been previously
reduced to the protoxide by the copper dissolving. When the
persulphate of iron is used for dissolving copper, and ammonia is
then added to the solution, the same results take place : — the pre-
cipitation of both copper and iron. But the compound seems not
so stable, the copper passing more quickly into an oxide, which
dissolves in the ammonia. However, with free ammonia, either
with the chloride or sulphate, the oxidation of the metals is slower
than with water alone.
Copper moulds intended for receiving a deposit must be pro*
tected on the back, but if the solution is very strong, there is every
danger that it will decompose the protecting substance, thus ren-
dering the solution very dirty, and causing a sediment. For the
purpose of protecting the mould, various suggestions and experi-
ments have been made ; amongst other substances, pitch has been
tried: it is easily affected alone, but on boiling a little of it in pot-
ash, a heavy and dirty sediment is left, destitute of any adhesive
property ; on putting a quantity of this sediment into a pot nearly
tilled with melted pitch, a violent effervescence will take place, set-
ting free a volume of white fumes having a creosotic smell. After
all effervescence has ceased, which will not be before a considerable
time, and when all the mass seems to have been acted upon, the
process of making an excellent protecting coating is completed — a
coating which will not yield in the solution, and which is at once
both good and cheap, its only fault being its brittleness.
In the manufacture of solid silver articles, the electro-process
has not yet been of extensive application : and in making dupli-
cates of rare objects of art, and costly chased or engraved articles
in silver, one prevailing objection has been felt, namely, they have
no "ring," and seem, when laid suddenly upon a table, to be
cracked or unsound, or like so much lead; this disadvantage is no
iloubt partly owed to the crystalline character of the deposit, and
ELECTRO-PLATING. 609
partly to the pure character of the silver, in which state it has not
a sound like standard or alloyed silver. That this latter cause is
the principal one, appears from the fact that a piece of silver thus
deposited is not much improved in sound by being heated and
hammered, which would destroy all crystallization.
We may mention that the same objections are applicable to
articles made in gold by the electro-deposit ; nevertheless, for fig-
ures and ornaments, these objections are of little weight. When
in Marlborough House a few months back, we were shown a plate
of antique pattern in deposited silver, which was all but free from
these defects.
DEAD SILVERING FOR MEDALS. — The perfect smoothness which a
medal generally possesses on the surface, renders it very difficult to
obtain a coating of dead silver upon it, having the beautiful silky
lustre which characterizes that kind of work, except by giving it a
very thick coating of silver, which takes away the sharpness of the
impression. This dead appearance can be easily obtained by put-
ting the inedal, previous to silvering, in a solution of copper, and
depositing upon it, by means of a weak current, a mere blush of cop-
per, which gives the face of the medal that beautiful crystalline rich
ness that deposited copper is known to give. The medal is then
to be washed from the copper solution, and immediately to be put
into the silver solution, A very slight coating of silver will suffice
to give the dead frosty lustre so much admired, and in general so
difficult to obtain.
OXIDIZING SILVER. — A very beautiful effect is produced upon
the surface of silver articles technically termed oxidizing, which
gives the surface an appearance of polished steel. This can be
easily effected by taking a little chloride of platinum, prepared as
described at page 527, heating the solution and applying it to the
silver when an oxidized surface is required, and allowing the solu-
tion to dry upon the silver. The darkness of the color produced
varies according to the strength of the platinum solution, from a
light steel gray to nearly black. The effects of this process, when
done along with what is termed dead work, is very pretty, and may
be easily applied to medals, giving scope for the exercise of taste.
Upon this we quote the following :
"The high appreciation in which ornaments in oxidized silver
are now held, render a notice of the process followed interesting.
There are two distinct shades in use, one produced by chloride,
which has a brownish tint, and the other by sulphur, which has a
bluish black tint. To produce the former, it is only necessary to
wash the article with a solution of sal-ammoniac ; a much more
beautiful tint may, however, be obtained by employing a solution
composed of equal parts of sulphate of copper and sal-ammoniac
in vinegar. The fine black tint may be produced by a slightly
warm solution of sulphu ret of potassium or sodium."- -Chem. Techn.
Mittheihmgen von Dr. Ellsner.
PROTECTION OF SILVER SURFACE. — All silver or plated articles
39
610 THE PRACTICAL METAL-WORKER1* ASSISTANT.
are subject to tarnish by exposure to the air, especially in this cli
mate, and where coals containing so much sulphur are used; the
tarnish being generally a sulphuret of silver. Deposited silver is
more easily tarnished than standard silver.
Medals or figures silvered. for the sake of their appearance ought
to be protected from the air, or they very soon lose their silver
color; a medal may be put into a frame air-tight, and a figure
should be covered with a glass shade : if the silver has been left
dead, any attempt to clean it destroys its appearance. Varnishes
have been tried to protect the silver from the atmosphere ; but all
varnishes, however colorless, detract from the silver lustre, and are
not good. For ordinary purposes, medals may be very conve-
niently protected by laying a piece of common glass over the sur-
face, cut to the exact size, and held close by a piece of paper pasted
round the edges of both, and then a stout piece on the back. We
have had silver medals, preserved by this means, for more than ten
years. Little round medals may be conveniently covered by watch-
glasses, fastened on in the same manner.
CLEANING OF SILVER. — A weak solution of cyanide of potassium,
used as a wash over tarnished silver, will brighten it. This solu-
tion was, and we believe is still, sold in small bottles for this pur-
pose, but it is not good, as it dissolves the silver rapidly, and is
such a deadly poison that it must be used with great caution on
articles that may be required for domestic purposes.
A variety of cleaning pastes and powders are used for silver or
plated goods. Those containing mercury and oxide of lead should
be avoided, for although they give a dark color when newly put
on, it soon blackens. The best paste we have found is a mixture
of fine precipitated chalk, carbonate of magnesia, and oxide of iron.
These materials are made into a paste, and rubbed upon the plate
with soft leather: for wrought or chased surfaces a hard brush is
best. The goods should be finished by polishing with leather and
a little of this mixture in a dry state, which will give that fine dark
mirror-looking color so much admired. Common coarse whiting
and flannel cloths should not be used, as thev wear the silver
rapidly.
CHAPTER XXXI.
ELECTRO- GILDING.
THE operation of gilding, or covering other metals with a coa'
ing of gold, is performed in the same manner as the operation of
plating, with the exception of a few practical modifications, which
iv e shall now notice in detail.
PREPARATION OF SOLUTION OF GOLD. — The gold solution for
ELECTRO-GILDING. 611
gilding -is prepared by dissolving gold in three parts of muriatic
acid and one of nitric acid, which forms the chloride of gold.
This is digested with calcined magnesia, and the gold is precipi
tated as an oxide. The oxide is boiled in strong nitric acid, which
dissolves any magnesia in union with it: the oxide being well
washed is dissolved in cyanide of potassium, which gives cyanide
of gold and potassium ; thus : —
Substances used: Substances produced:
Oxide of Gold = AuO Cyanide of Gold]
2. Cyanide of Potassium=2KCy and Potassium )
Potash =KO
Auo +2 KCy=KO+(KCy + AuCy.)
By this method a proportion of potash is formed in the solution,
as an impurity ; it is not, however, very detrimental to the process.
In preparing the oxide of gold there is always a little of the gold
lost, to recover which the washings should be kept, evaporated to
dryness, and fused.
Another and very simple method is this : — Add a solution of
cyanide of potassium to the chloride of gold until all the precipi-
tate is redissolved ; but this gives chloride of potassium in the so-
lution, which is not good. In the preparation of the solution by
this means there are some interesting reactions. As the chloride
of gold has always an excess of acid, the addition of cyanide of
potassium causes "violent effervescence, and no precipitate of gold
takes place until all the free acid is neutralized, which causes a
considerable loss to the cyanide of potassium. There is always
formed in this deposition a quantity of ammonia and carbonic acid,
from the deposition of the cyanate of potash ; and if the chloride
of gold be recently prepared and hot, there is often formed somt;
aurate of ammonia (fulminate of gold), which precipitates with the
cyanide of gold. Were this precipitate to be collected and dried,
it would explode when slightly heated. On previously diluting
the chloride of gold, or using it cold, this compound is not formed.
After the free acid is neutralized by the potash, further addition
of the cyanide of potassium precipitates the gold as cyanide of
gold, having a light yellow color ; but as this is slightly soluble in
ammonia and some of the alkaline salts, it is not advisable to wash
the precipitate lest there be a loss of gold. Cyanide of potassium
is generally added until the precipitate is redissolved ; conse-
quently much impurity is formed in the solution, namely, ni-
trate and carbonate of potash with chloride of potassium and
ammonia. Notwithstanding, this solution works very well for
a short time, and it is very good for operations on a small
scale.
BATTERY PROCESS OF PREPARING GOLD SOLUTION. — The best
method of preparing the gold solution is that described for silver
(p. 589). Say the operator wishes to prepare a gallon of gold so-
(J12 THE PRACTICAL METAL-WORKER'S ASSISTANT.
lution, he dissolves four ounces of cyanide of potassium in one
gallon of water, and heats the solution to 150° Fah. ; he now takes
a small porous cell and fills it with this cyanide solution, and places
it inside the gallon of solution : into this cell is put a small plate
of iron or copper, and attached by a wire to the zinc of a battery.
A piece of gold is placed into the large solution, facing the plate
in the porous cell, and attached to the copper of the battery. The
whole is allowed to remain in action until the gold, which is to be
taken out from time to time and weighed, has lost the quantity re-
quired in solution. By this means a solution of any strength can
be made, according to the time allowed. The solution in the
porous cell, except the action has continued long, will have no
gold, and may be thrown away. Half an hour will suffice for a
small quantity of solution — of course any quantity of solution
may be made up by the same means. For all the operations of
gilding by the cyanide solution, it must be heated to at least 130°
Fah. The articles to be gilt are cleaned in the way described for
silver, but are not dipped into nitric acid previously to being put
in the gold solution. Three or four minutes is sufficient time to
gild any small article. After the articles are cleaned and dried
they are weighed — and when gilt they are weighed again ; thus
the quantity of gold deposited is ascertained. Any convenient
means may be adopted for heating the solution. The one generally
adopted is to put a stoneware pan containing the solution into an
iron or tinplate vessel filled with water, which is kept at the boil-
ing point either by being placed upon a hot plate or over gas.
The hotter the solution the less battery power is required. Gen-
erally three or four pairs of plates are used for gilding, and the
solution is kept at 130° to 150° Fah. But one pair will answer
if the solution is heated to 200°.
PROCESS OF GILDING. — The process of gilding is generally per-
formed upon silver articles. The method of proceeding is as fol-
lows : When the articles are cleaned as described in our chapter
on plating, they are weighed, and well scratched with wire brushes,
which cleanse away any tarnish from the surface, and prevents the
formation of air-bubbles. They are then kept in clean water until
it is convenient to immerse them in the gold solution. One im-
mersion is then given, which merely imparts a blush of gold ;
they are taken out and again brushed; they are then put back into
the solution and kept there for three or four minutes, which will
be sufficient if the solution and battery are in good condition ; but
the length of time necessarily depends on these two conditions,
which must be studied and regulated by the operator.
Iron, tin, and lead, are very difficult to gild direct ; they there-
fore generally have a thin coating of copper deposited upon them
by the cyanide of copper solution and immediately put into the
gilding solution.
CONDITIONS REQUIRED IN GILDING. — The gilding solution gen-
erally contains from one-half to an ounce of gold in the gallon, but
ELECTRO-GILDING. 613
for covering small articles, such as medals, for tinging daguerreo-
types, gilding rings, thimbles, etc., a weaker solution will do. The
solution should be sufficient in quantity to gild the articles at once,
so that it should not have to be done bit by bit ; for when there is
a part in the. solution and a part out, there will generally be a line
mark at the point touching the surface of the solution. The
rapidity with which metals are acted upon at the surface line of the
solution is remarkable. If the positive electrode is not wholly
immersed in the solution, it will, in a short time, be cut through
at the surface of the water, as if cut by a knife. This is also
the case in silver, copper, and other solutions, as before referred to.
MAINTAINING THE GOLD SOLUTION. — As the gold solution
evaporates by being hot, distilled water must from time to time be
added. The water should always be added when the operation
of gilding is over, not when it is about to be commenced, or the
solution will not give so satisfactory a result. When the gilding
operation is continued successively for several days, the water
should be added at night. The average cost of depositing gold is
about 4 cts. per pennyweight.
The means of testing the free cyanide of potassium, with nitrate
of silver, as described for silver, is not applicable to the gold solu-
tion ; but it may be tested by the ammoniuret of copper, see p. 603.
To obtain a deposit of a good color much depends upon the state
of the solution and battery ; it is therefore necessary that strict
attention be paid to these, and more so as the gold solution is very
liable to change if the relative size of the article receiving the
deposit is not according to that of the positive plate.
The result of a series of observations and experiments, con-
tinued daily throughout a period of nine months, showed that in
five instances only the deposit was exactly equal to the quantity
dissolved from the positive plate. In many cases the difference
did not exceed 3 per cent., though occasionally it rose to 50 per cent.
The average difference however was 25 per cent In some cases
double the quantity dissolved was deposited, in others the reverse
occurred — both resulting from alterations made in the respective
processes ; for in these experiments we varied, as far as practicable,
the state of the solution and the relative sizes of the negative and
positive electrodes.
The most simple method of keeping a constant register of the
state of the solution is to weigh the gold electrode before putting
it into the solution ; and, when taking it out, to compare the loss
with the amount deposited : a little allowance, however, must bo
made for small portions of metal dissolved in the solution, from
the articles that are gilt, which, when gilding is performed daily,
is considerable in a year. A constant control can thus be exer-
cised over the solution, to which there will have to be added from
time to time a little cyanide of potassium, a simple test of require-
ment being that the gold pole should always come out clean — for
if it has a film or crust it is a certain indication that the solutiou
014 THE PRACTICAL METAL-WORKER^ ASSISTANT.
is deficient of cyanide of potassium. Care must be taken to dL-
tinguish this crust, which is occasionally dark-green or black, from
a black appearance which the gold pole witl take when very small
in comparison to the article being gilt, and which is caused by
the tendency to evolve gas. In this case an addition of cyanide
of potassium would increase the evil. The black appearance from
the tendency to the escape of gas has a slimy appearance. This
generally takes place when the solution is nearly exhausted of
gold, of which fact this appearance, taken conjointly with the rela-
tive sizes of the electrodes, are a sure guide.
To REGULATE THE COLOR OF THE GILDING.— The gold upon
the gilt article, on coming out of the solution should be of a dark-
yellow color, approaching to brown, but this when scratched will
yield a beautifully -rich deep gold. If the color is blackish it
ought not to be finished, for it will never either brush or burnish
a good color. If the battery is too strong, and gas is given off
from the article, the color will be black ; if the solution is too
eold, or the battery rather weak, the gold will be light-colored ;
so that every variety of shade may be imparted. A very rich dead
gild may be made by adding ammoniuret of gold to the solution
just as the articles are being put in, or what is better, add some
sulphuret of carbon in the same way as for silver solutions, which
affects the color and appearance of the gold in the same way as it
does the silver.
COLORING OF GILDING. — A defective colored gilding may be im-
proved by the same method as that adopted in the old process to
color gilding or gold, namely, by the help of the following mixture •
8 parts Nitrate of Potash
1J Alum
1J Sulphate of Zinc
1J Common Salt.
These ingredients are put into a small quantity of water, to form
a sort of paste, which is put upon the articles to be colored : they
are then placed upon an iron plate over a clear fire, so that they will
attain nearly to a black heat, when they are suddenly plunged intr-
cold water : this gives them a beautiful high color. Different hues
may be had by a variation in the mixture.
To DISSOLVE GOLD FROM GILT ARTICLES. — Before regilding
articles which are partly covered with gold, or when the gilding is
imperfect, and the articles require regilding, the gold should be
removed from them by putting them into strong nitric acid ; and
when the articles have been placed in the acid, by adding some
common salt, not in solution, but in crystals. By this method gold
may be dissolved from any metal, even from iron, without injuring
it in the least. After corning out of the acid, the articles must be
polished. The best method, however, is to brush off the gold as
described fjr silver (page 597), which gives the polish at the same
time.
ELECTRO-GILDING. 615
To RECOVER THE GOLD. — When the gold is dissolved off by the
acid after it is saturated, or when it ceases to dissolve the gold
rapidly, the acid is diluted with several times its bulk of water,
and then soda or potash added till the greater portion of the acid
is neutralized. A solution of sulphate of iron (copperas) is then
added, so long as a precipitate is formed ; when this settles down
it is carefully collected upon a paper filter, washed and dried, and
then fused in a crucible with a little borax and common salt, when
the gold is found as a button at the bottom of the crucible.
When the gold is brushed oft] the brushings are burned at a red
heat, and the residue fused with carbonate of soda and a little
borax: in this case, the gold will not be pure and will have to be
refined.
OBJECTIONS TO ELECTRO-GILDING. — Objections have also been
made to the application of electro-gilding to the arts, of the same
kind as those urged against electro-plating ; but the now almost
universal adoption of this process by gilders, because of the perfec-
tion to which the articles are brought, forms the best answer we
can give to such objections. However, let us take a hasty glance
at the old process and its consequences, that we may be enabled
to judge of the comparative merits of both methods.
Before the introduction of electro-deposition, the only method of
gilding was by forming an amalgam of gold and mercury, which,
at the consistence of a thin paste, was brushed upon the articles
over a strong heat ; the mercury being gradually dissipated, the
gold remained fixed upon the articles. This process is most per-
nicious, and destructive to human life ; the mercury, volatilized by
the heat, insinuates itself into the bodies of the workmen, notwith-
standing the greatest care ; and those who are so fortunate as to
escape for a time absolute disease, are constantly liable to saliva-
tion from its effects. Paralysis is common among them, and the
average of their lives is very short; it has been estimated as not
.exceeding 35 years. It is difficult to believe that men could be
found to engage in such a business, reckless of the consequences so
fearfully exhibited before them; and it would naturally be thought
they would hail with pleasure the introduction of any process
which would be put a stop to such a dreadful sacrifice of human
life. But it is very difficult to overcome interest and prejudice,
even when the object to be gained is of such vast importance.
EFFECTS OF CYANOGEN ON HEALTH. — The effects produced
upon the health of those who work constantly over cvanide solu-
tions are not yet fully tested, by which we could form a compari-
son with the old process; for every new trade, or operation, gives
rise to a new disease, or some new forms of an old disease. Hav-
ing ourselves inhaled much of the fumes of that "ominous" gas
given off from the cyanide of potassium solution, we are not pre-
pared to stand its advocate, but would rather warn all employed at
the business, or who may in any degree have to do with these so-
lutions, to be very careful not to use too much freedom. The
THE PRACTICAL METAL-WORKER'S ASSISTANT.
Lands of those engaged in gilding or plating are subjected to ulcera-
tion, particularly if they have been immersed in the solution. The
ulcers are not only annoying but painful; and, on their first appear-
ance, if care is not properly taken to wash them in strong cyanide
of potassium, and then in acid water, the operator will, in a short
time, have to take a few days rest. We have repeatedly seen, by
the aid of a magnifying glass, gold and silver reduced in these
ulcerations. We have also known of eruptions breaking out over
the bodies of workmen after inhaling those deleterious fumes
when they were very bad, as when solutions were precipitated by
acids or being evaporated to dryness in a close apartment for the
recovery of the metal. Kepeatedly have we seen the legs of work-
men thus afflicted, and always after they have been exposed to
extra fumes.
The following statement of the general effects of electro-plating
and gilding on the health of those engaged in them, as experienced
by ourselves and others, may not be uninteresting to our readers :
but it is necessary to premise that the apartments in which we
were employed were improperly ventilated.
The gas has a heavy sickening smell, and gives to the mouth a
saline taste, and scarcity of saliva ; the saliva secreted is frothy.
The nose becomes dry and itchy, and small pimples are found
within the nostrils, which are very painful (we have felt these
effects in the nose from the hydrogen of the batteries, where there
were no cyanide solutions). Then follows a general languor of
body; disinclination to take food, and a want of relish. After
being in this state for some time, there follows a benumbing sensa-
tion in the head, with pains, not acute, shooting along the brow;
the head feels as a heavy mass, without any individuality in its
operations. Then there is bleeding at the nose in the mornings
when newly out of bed; after that comes giddiness; objects are
seen flitting before the eyes, and momentary feelings as of the earth
lifting up, and then leaving the feet, so as to cause a stagger. This
is accompanied with feelings of terror, gloomy apprehension, and
irritability of temper. Then follows a rushing of blood to the
head; the rush is felt behind the ears with a kind of hissing noise,
causing severe pain and blindness : this passes off in a few seconds,
leaving a giddiness which lasts for several minutes. In our own
case the rushing of blood was without pain, but attended with in-
stant blindness, and then followed with giddiness. For months
afterwards a dimness remained as if a mist intervened between us
and the objects looked at: it was always worse towards evening,
when we grew very languid and inclined to sleep. We rose com-
paratively well in the morning : yet were restless, our stomach
was acid, visage pale, features sharp, eyes sunk in the head, and
round them dark in color: these effects were .slowly developed.
Our experience was nearly three years.
We have been thus particular in detailing these effects, as a
warning to all employed in the process ; but we have no doubt that
COATING WITH VARIOUS METALS. 617
in lofty rooms, airy and well ventilated, these effects would not be
felt. Employers would do well to look to this matter ; and ama-
teurs, who only use a small solution in a tumbler, should not, as
the custom sometimes is, keep it in their bed-rooms; the practice is
decidedly dangerous.
PRACTICAL SUGGESTIONS IN GILDING. — According to the amount
of gold deposited, so will be its durability: a few grains will serve
to give a gold color to a very large surface, but it will not last: this
proves, however, that the process may be used for the most inferior
quality of gilding. Gold thinly laid upon silver will be of a light
color, because of the property of gold to transmit light. The so-
lution for gilding silver should be made very hot, but for copper
it should be at its minimum heat. A mere blush may be sufficient
for articles not subjected to wear ; but on watch-cases, pencil-cases,
chains, and the like, a good coating should be given. An ordi-
nary sized watch-case should have from 20 grains to a penny-
weight ; a mere coloring will be sufficient for the inside, but the
outside should have as much as possible. A watch-case thus gilt,
for ordinary wear, will last five or six years without becoming
bare. We have known some to be in use full six years without
losing their covering. Small silver chains, such as those sold at
eight shillings, should have 12 grains ; pencil-cases, of ordinary
size should have from 3 to 5 grains ; a thimble from 1 to 2 grains.
These suggestions will serve as a guide to amateur gilders, many
of whom, having imparted only a color to their pencil-cases, feel
chagrin and disappointment upon seeing them speedily become
bare; hence arises much of the obloquy thrown upon the process.
CHAPTER XXXII.
RESULTS OF EXPERIMENTS ON THE DEPOSITION ON OTHER METALS
AS COATINGS.
COATING WITH PLATINUM. — This metal has never yet been suc-
cessfully deposited as a protecting coating to other metals. A solu-
tion may be made by dissolving it in a mixture of nitric and muri-
atic acids, the same as is employed in dissolving gold ; but heat
must be applied. The solution, is then evaporated to dryness, and
to the remaining mass is added a solution of cyanide of potassium ;
next, it must be slightly heated for a short time, and then filtered
This solution, evaporated, yields beautiful crystals of cyanide of
platinum and potassium; but it is unnecessary to crystallize the salt.
A very weak battery power is required to deposit the metal : the
solution should be heated to 100°. Great care must be taken to
obtain a fine metallic deposit : indeed the operator may not sue
618 THE PRACTICAL
ceed once in twenty times in. getting more than a mere coloring of
metal over the surface, and that not very adhesive. The causes of
the difficulty are probably these : the platinum used as an electrode
is not acted upon; the quantity of salt in solution is very little; it
requires a particular battery strength to gives a good deposit, and
the slightest strength beyond this gives a black deposit ; so that,
were the proper relations obtained, whenever there is any deposit,
the relations of battery and solution are changed, and the black
pulverulent deposit follows.
We have occasionally succeeded in obtaining a bright metallic
deposit of platinum, possessing the qualities of adhesion and dura-
bility : some of the articles thus covered presented no signs of
change after many years : but we have never been so fortunate as
to get a platinum deposit that could protect any metal from the
action of acids, or other fluids by which the metal could be affected.
We have covered iron, such as the end of a glass-blower's blow-
pipe, so that it could be made red-hot without the iron rusting, but
rather taking the characteristic appearance of platinum: but even
that did not protect the iron from rusting when it was put a short
time into water, or kept exposed to moist air. We have seen again
and again recommendations of certain solutions of platinum for the
purpose of obtaining a reguline metal, and no doubt it has been
obtained, but, as stated above, we believe more incidentally than
at will. The protoxalate of platinum has been strongly recom-
mended for covering copper and brass with platinum.*
COATING \VITH PALLADIUM. — Palladium is a metal very easily
deposited. The solution is prepared by dissolving the metal in
nitro- muriatic acid, and evaporating the solution nearly to dry-
ness ; then adding cyanide of potassium till the whole is dissolved :
the solution is then filtered and ready for use. The cyanide of
potassium holds a large quantity of this metal in solution, and the
electrode is acted upon while the deposit is proceeding. Articles
covered with this metal assume the appearance of the metal ; but
so far as we are aware, it has not yet been applied to any practical
purpose. It requires rather a thick deposit to protect metals from
the action of acids, which is, probably, the only use it can be
applied to.
COATING WITH NICKEL.— Nickel is very easily deposited ; and
may be prepared for this purpose by dissolving it in nitric acid,
then adding cyanide of potassium to precipitate the metal ; after
which the precipitate is washed and dissolved by the addition of
more cyanide of potassium. Or the nitrate solution may be pre-
cipitated by carbonate of potash; this should be well washed, and
then dissolved in cyanide of potassium; a proportion of. carbonate
of potash will be in the solution, which we have not found to be
detrimental. This latter method of preparing the nickel plating
solution is simple, and, therefore, has our recommendation. The
* Polyteohni. Coustuh. 1855.
COATING WITH VARIOUS ME1ALS. 619
metal is very easily deposited; it yields a color approaching to
silver, which is not liable to tarnish on exposure to the air. A
coating of this metal would be very useful for covering common
work such as gasaliers, and other gas-fittings, and even common
plate. The great difficulty experienced is to obtain a positive
electrode : the metal is very difficult to fuse, and so brittle that we
have never been able to obtain either a plate or a sheet of it.
Could this difficulty be easily overcome, the application of nickel
to the coating of other metals would be extensive, and the property
of not being liable to tarnish would make it eminently useful for
all general purposes. We coated articles with nickel in 1845,
which were exposed to the air for many years without tarnish,
and when last seen by the author exhibited no change.
ANTIMONY, ARSENIC, TIN, IRON, LEAD, BISMUTH, AND CADMIUM.
— We have deposited these metals from their solutions in cyanide
of potassium; but not for any useful application.
IRON. — Iron may be very easily deposited from its sulphate:
dissolve a little crystalline sulphate of iron in water, and add a few
drops of sulphuric acid to the solution : one pair of Smee's battery
may be used to deposit the iron upon copper or brass. The metal
in. this pure state has a very bright and beautiful silver color.
LEAD. — Lead may be deposited from a solution of an acid salt,
such as the acetate, bu.t requires some management or strength of
battery: it may also be deposited from its solution in potash or
soda.
ALUMINIUM AND SILICIUM. — Since the publication of the former
edition of this work, new methods have been discovered for obtain-
ing the base or metal of alumina and silica, or clay and sand, in
i he metallic state possessing extraordinary properties. One of the
methods successfully adopted, is by fusing in a small crucible
some chloride or fluoride of aluminium, and when in fusion, in-
serting two steel poles in connection with a battery which reduces
the salt, giving small globules of the rnetal aluminium.
Attempts have also been made to deposit the metals from their
cyanous solution as coating upon other metals in the usual way.
We have not ourselves tried any experiments upon these metals,
but we take the following results of experiments from Mr. G. Gore
of Birmingham, who seems to have given the subject a good deal
of attention :
"It has long been known to chemists that all kinds of clay,
stone, and sand, of which the earth is composed, consist of metals
combined with oxygen, carbonic acid, sulphuric acid, and other
non-metallic elements, forming therewith oxides, carbonates, sul-
phates, etc.; thus clay is an oxide of aluminium, sand an oxide of
silicium, limestone a carbonate of calcium ; but the separation of
the metallic bases from the non-metallic elements with which they are
combined has been a matter of so great difficulty, that few chemists
have put themselves to the trouble of accomplishing it, and those
who have done so have made use of the most powerful means and
620 THE PRACTICAL METAL-WORKER 's ASSISTANT.
reducing agents, such as large voltaic batteries, potassium, etc.,
and have then obtained them in a state of alloy or combination
with mercury. Sir Humphrey Davy, the discoverer of most of
these bases, in his experiments on the decomposition of the alkalies
and earths, used a powerful battery, consisting of 500 pairs of
plates, and then succeeded in obtaining them combined with mer-
cury, from which they were afterwards separated. Wohler and
Berzelius, in their discoveries of the means of separating the metals
aluminium and silicium from their respective compounds, clay and
sand, used a high temperature and potassium, and then succeeded
in obtaining them in the condition of dull metallic powders, nearly
infusible.
" By a means recently discovered, and described in the March
number of the Philosophical Magazine for this year, I have suc-
ceeded in depositing the metals aluminium from clay, and silicium
from sandstone, each in a perfect metallic condition, by dissolving
pipe clay, common red sand, pounded stone, etc., in various chemical
liquids, and passing currents of electricity from ordinary small
voltaic batteries through the solutions.
'' My attention has since been directed to produce simple pro-
cesses, whereby any person not possessing a knowledge of chem-
istry may readily coat articles with those metals, and thus cause
the discovery to be immediately applied to human benefit in the
arts and manufactures, and the following are the results of my ex-
periments :
" To coat articles of copper, brass, or German silver, with alumi-
nium, take equal measures of sulphuric acid and water, or take one
measure each of sulphuric and hydrochloric acids and two mea-
sures of water ; add to the water a small quantity of pipe-clay, in
the proportion of 5 or 10 grs. by weight to every ounce by mea-
sure of water (or J oz. to the pint): rub the clay with the water
until the two are perfectly mixed, then add the acid to the clay
Sv)lution, and boil the mixture in a covered glass vessel one hour.
Allow the liquid to settle, take the clear, supernatant solution,
while hot, and immerse in it an earthen porous cell, containing a
mixture of one measure of sulphuric acid and ten measures of
water, together with a rod or plate of amalgamated zinc ; take a
small Smee's battery, of three or four pairs of plates, connected
together intensity fashion, and connect its positive pole by a wire,
with a piece of zinc in the porous cell. Having perfectly cleaned
the surface of the article to be coated, connect it by a wire with
the negative pole of the battery, and immerse it in the hot clay
solution ; immediately abundance of gas will be evolved from the
whole of the immersed surface of the article, and in a few minutes,
if the size of the article is adapted to the quantity of the current
of electricity passing through it, a fine white deposit of aluminium
will appear all over the surface. It may then be taken out, washed
quickly in clean water, and wiped dry, and polished ; but if a
thicker coating is required, it must be taken out when the deposit
COATING WITH VARIOUS METALS. 621
becomes dull in appearance, washed, dried, polished, and re-im-
mersed ; and this must be repeated at intervals, as often as it be-
comes dull, until the required thickness is obtained. With small
articles it is not absolutely necessary, either in this or the follow-
ing process, that a separate battery be employed, as the article to
be coated may be connected by a wire with a piece of zinc in the
porous cell, and immersed in the outer liquid, when it will receive
a deposit, but more slowly than when a battery is employed.
" To coat articles with silicium, take the following proportions :
three-quarters of an ounce, by measure, of hydrofluoric acid, J oz.
of hydrochloric acid, and 40 or 50 grs. either of precipitated silica,
or of fine white sand (the former dissolves most freely), and boil the
whole together for a few minutes, until no more silica is dissolved.
Use this solution exactly in the same manner as the clay solution,
and a fine white deposit of metallic silicium will be obtained, pro-
vided that the size of the article is adapted to the quantity of the
electric current : common red sand, or indeed any kind of silicious
stone, finely powdered, may be used in place of the white sand, and
with equal success, if it be previously boiled in hydrochloric acid,
to remove the red oxide of iron or other impurities.
" Both in depositing aluminium and silicium, it is necessary to
well saturate the acid with the solid ingredients by boiling, other-
wise very little deposit-of metal will be obtained.
" Among the many experiments I have made upon this subject,
the following area few of the most interesting: —
"Experiment 1. — Boiled some pipe-clay in caustic potash and
water, poured the clear part of the solution into a glass vessel, and
immersed in it a small earthen porous cell, containing dilute sulphuric
acid and a piece of amalgamated zinc ; immersed a similar piece of
bright sheet copper in the alkaline liquid, and connected it with
the negative pole of a small Smee's battery of three pairs of plates,
connected the zinc plate with the positive pole, and let the whole
stand undisturbed all night ; on examining it next morning I found
the piece of copper coated with a white silver-like deposit of met-
allic aluminium.
''Experiment 2. — Obtained from a railway cutting in the town
a small piece of the sand rock upon which Birmingham is built,
boiled it in hydrochloric acid, to remove the red oxide of iron,
washed it clean with water, and dissolving it by boiling it in a mix-
ture of hydrofluoric acid, nitric acid, and water; immersed in this
solution, a porous cell with dilute acid and zinc, as before ; con-
nected a piece of brass with the zinc by a wire, and suspended it
in the outer liquid, which was kept hot by a small spirit lamp be-
neath ; after allowing the action to proceed several hours, I found
the piece of brass beautifully coated with white metallic silicium.
11 Experiment 3. — Took one part, by weight, of the same sand-
stone, after being purified by the hydrochloric acid, and 2J parts of
carbonate of potash, fused them together in a crucible until all
evolution of gas ceased, and a perfect glass was formed ; pouivd
022 THE PRACTICAL METAL-WORKER^ ASSISTANT.
out the melted glass, and when cold, dissolved it in water, and used
this solution in the same manner as the former ones, allowing the
action to proceed about 12 hours, when a good white deposit of
metallic silicium was obtained.
"Experiment 4. — Took some stones with which the streets of
Birmingham are macadamised, pounded them fine in a mortar, boiled
the powder in hydrochloric acid, to purify it from iron, washed it
well in water, and dissolved it by-boiling an excess of it in a mix-
ture of f oz., by measure, of hydrofluoric acid, J oz. of water, arid
J oz. each of nitric and hydrochloric acids, until no more would
dissolve; used the clear portion of this solution in the same man-
ner as the former liquids, and readily coated in it a piece of brass
with a beautifully white deposit either of aluminium or silicium.
From these, and many other experiments which I have tried, it is
quite clear that common metal articles may be readily coated with
white metals, possessing similar characters to silver, from solutions
of the most common and abundant materials, and thus bring within
the purchase of the poorer classes articles of taste and cleanliness
which are at present only to be obtained by the comparatively
wealthy."
TIN. — Tin is easily deposited from a solution of protochloride
of tin. If the two poles or electrodes be kept about two inches
apart, a most beautiful phenomenon may be observed. The de-
composition of the solution is so rapid that it shoots out from the
negative electrode like tentacula, or feelers, towards the positive,
which it reaches in a few seconds. The space between the poles
seems like a mass of crystallized threads, and the electric current
passes through them without effecting further decomposition. So
tender are these metallic threads that when lifted out of the solu-
tion they fall upon the plate like cobweb. Seen through a glass
they exhibit a beautiful crystalline structure. If a circular elec-
trode of tin is used, and a small wire put in the centre of the
chloride solution, the thread-like crystals will shoot out all round,
and give quite a metallic confervas. Tin may also be deposited
from its solution in caustic potash or soda.
ANTIMONY. — In the deposition of antimony Mr. Gore has ob-
served a curious and interesting phenomenon, that the metal during
its. deposition, and after some has been deposited, explodes occa-
sionally, the particles being thrown about by the shock.
DEPOSITION OF ALLOYS. — Many attempts have been made to
deposit alloys of rnetals from their solutions. That two or more
metals can be deposited from a solution we have seen sufficient
evidence ; but the means to regulate the proportions of each, and
to make such a process practical, have yet to be discovered. It is
hardly possible to get a mixed solution of any two metals that are
exactly equally decomposable ; or, in other wprds, that the metals
under the circumstances in which they are placed are exactly of
equal conducting power. Hence the electric current will always
travel through the one that offers the least resistance, and theic
COATING WITH VARIOUS METALS. 623
will be none of the other metallic solution decomposed, or metal
deposited, until the quantity of electricity is greater than the best
conducting metal in the solution will allow to pass ; then the other
metal will be deposited in proportion to the extra electrical power
that passes. As, for example, take a mixture of cyanide of gold,
silver, and copper, in cyanide of potassium. The silver in this
state is so much superior in its conducting power to the other salts,
that all the silver may be deposited from the solution by a weak
battery without any of the other metals. If the solution be after-
wards heated, and the battery power kept so that no gas is allowed
to escape from the articles, the gold may be deposited without any
copper; but if the gas is allowed to flow from the article receiving
the deposit, the copper will be deposited, and often more abun-
dantly than the gold, as the escape of gas is not consistent with a
reguline deposit of gold. We have thus deposited an alloy of
gold and copper ; we have also deposited gold and silver, but the
alloy was very inferior and irregular. Alloys can be obtained
from silver and palladium, from cyanide solutions, from zinc and
copper, from a solution of their sulphates ; but in no instance have
we found good alloys, or alloys that could pass as such in name or
appearance. We have seen articles, such as iron, covered with
copper and zinc in this manner, or in alternate layers, and the
articles having the coating heated in charcoal, by which means a
brass of fair appearance was obtained, but the process is attended
with practical difficulty, and the product cannot be called deposited
brass.
Several patents have been taken out for the deposition of
alloys of various sorts. The following, by Morris and John&on,
embraces a wide range, and being well described we will copy the
specification :
" This invention consists in the employment of solutions com-
posed of cyanide of potassium and carbonate of ammonia, to
which are added cyanides, carbonates, and other compounds of
metals, in proportions according to the amount of deposit required
to be made.
" In order that the invention may be fully understood and car-
ried into effect, the patentees proceed to describe the means pursued
by them as follows : These improvements consist in the employ-
ment of solutions composed of carbonate of amrnoiaa (the carbon-
ate of ammonia of commerce, or the sesqui-carbonate of ammonia
of chemists), and cyanide of potassium, to which are added car-
bonates, cyanides, or other compounds of metals, in various pro-
portions. For the well-known alloy, brass, carbonate of ammonia
and cyanide of potassium are used in the following proportions,
namely — To each or every gallon of water are added 1 Ib. of
carbonate of ammonia, 1 Ib. of cyanide of potassium, 2 ozs. of
cyanide of copper, and 1 oz. of cyanide of zinc. These propor-
tions may be varied to a considerable extent. Or the patentees
take the before-named solution of carbonate of ammonia and
cyanide of potassium, in the proportion of 1 Ib. of each to one
gallon of water ; and they take a large sheet of brass of the de-
sired quality, and make it the anode or positive electrode, in the
aforesaid solution, of a powerful galvanic battery or magneto-
electric machine, and a small piece of metal, and make it the
cathode or negative electrode, from which hydrogen must be
freely evolved. This operation is continued till the solution has
taken up a sufficient quantity of the ^brass to produce a reguline
deposit. The solution may be used cold ; but it is desirable, in
many cases, to heat it (according to the nature of the article or
articles to be deposited upon) up to 212° Fahr. For wrought or
fancy work about 150° Fahr. will give excellent results. The
galvanic battery, or magneto-electric machine, must be capable of
evolving hydrogen freely from the cathode or negative electrode,
or article attached thereto. It is preferred to have a large anode or
positive electrode, as this favors the evolution of hydrogen. The
article or articles treated as before described will immediately be-
come coated with brass. By continuing the process any desired
thickness may be obtained. Should the copper have a tendency to
come down in a greater proportion than is desired, which may be
known by the deposit assuming too red an appearance, it is cor-
rected by the addition of carbonate of ammonia, or by a reduction
of temperature, when the solution is heated. Should the zinc have
a tendency to come down in too great a proportion, which may be
seen by the deposit being too pale in its appearance, this is cor-
rected by the addition of cyanide of potassium or by an increase
of temperature.
" The alloy, German silver, is deposited by means of a solution
consisting of carbonate of ammonia and cyanide of potassium (in
the proportions previously given for the brass), and cyanides or
other compounds of nickel, copper, and zinc, in the requisite pro-
portions to constitute German silver. It is however preferred to
make the solution by means of the galvanic battery or magneto-
electric machine, as above described for brass. Should the copper
of the German silver come down in too great a proportion, this is
corrected by adding carbonate of ammonia, which brings down the
zinc more freely ; and 'should it be necessary to bring down the
copper in greater quantity, cyanide of potassium is added — such
treatment being similar to that of the brass before described.
"The solutions for the alloys of gold, silver, and other alloys of
metals, are made in the same manner as above stated, by emplov-
ing anodes of the alloy or alloys to be deposited ; or by adding to
the solutions the carbonates, cyanides or other compounds, in the
proportions forming the various alloys — always using in depositing
an anode of the required alloy. These solutions are subject to the
same treatment and control as those of the brass and German silver
before described.
" The patentees claim the combination of the carbonate of am-
, before named or other carbonates of ammonia and cyanide
COATING WITH VARIOUS METALS. 625
of potassium, as the ingredients for their solutions for depositing
alloys of metals."
The expense of depositing common metals will remain a barrier
to the use of electro-metallurgy in making such alloys as brass, a
consideration which some patentees do not seem to consider. We
have the following given as methods for mixing up solutions for
depositing brass, which will prove our position :
"As an illustration of this invention we take the patentee's
method of depositing a coating of brass by galvanic agency, in
which he employs the following : — 1. A solution of the double
chloride of zinc and ammonia. — 2. A solution of the double chlo-
ride of zinc and potassium. — 3. A solution of the double chloride
of zinc and sodium. — 4. A solution of the double acetate of zinc
and ammonia. — 5. A solution of the double acetate of zinc and
potassium. — 6. A solution of the acetate of zinc and soda. — 7. A
saturated solution of carbonate of zinc, and carbonate of ammonia.
— 8. A solution of the double tartrate of zinc, and of potash, soda,
or ammonia. (To one thousand parts of the solution of tartrate
of zinc, indicating three degrees on the salinometer, thirty parts of.
hydrochlorate of ammonia, and eighty parts of hydrochloric acid
must be added.) — 9. A solution of citrate of zinc rendered soluble
by an excess of citric acid. — 10. A solution of tartrate of zinc in
potash or soda. With each of the above solutions an analogous
solution of copper must be mixed in the proportion suitable for
obtaining the required depth of color."
Besides the ordinary electro-metallurgical operations, the public
are from time to time told through the press .that the process has
been applied to the extraction of metals from their ores, but on
examination the statement is invariably found to be incorrect, the
metal being in all cases separated from the ore by means of an acid
or acids, and the electro-metallurgical operations not applied till
after this separation takes place ; so that its application is altogether
apart from the extraction of the metal from the ore. Such an ap-
plication for common metals is commercially absurd ; and nothing
can exhibit the want of practical application so much as some of
the patents taken out for this object. The greater number of these
patents are intended for copper ores, upon which we will offer a
few remarks. It will be seen from the principles of deposition,
that, allowing the copper was all in solution to be deposited by a
battery, the cheapest form known will give the loss of one ton of
zinc and sulphuric acid to get one ton of copper, which would be
upwards of £20 for the materials destroyed, while a ton of copper
may be smelted by the ordinary process for half that sum. We
give the following extract of a patent as an illustration, not be-
cause it is worse than others, but being more definite in its methods
and battery than most of these patents, and the patentee an excel-
lent electrician.
"Mr. Andrew Crosse, of Broomfield, the electrician, has just
specified his patent for improvements in the extraction of metaJa
40
626 THE PRACTICAL METAL- WORKER'S ASSISTANT.
from their ores. The apparatus employed for this purpose con-
sists of a wooden or earthenware vessel capable of holding from
250 to 300 quarts, at a short distance above the bottom of which
is a movable platinum frame covered with a netting of platinum
wire, the meshes being about 1 inch each way. This frame is con-
nected to the positive pole of a Daniell's battery by a platinum
wire, covered with a non-conducting material throughout those
parts of it exposed to the liquid in the vessel ; the negative pole
of the battery being connected to a copper wire, from which is
suspended by three smaller wires, in the interior of the vessel, a
bowl of wood lined with sheet copper and covered with a cop-
per wire netting. The battery in connection with the appara-
tus should consist of 20 pairs of plates, each in a gallon glass
vessel, filled with a saturated solution of sulphate of copper,
to which has been added from l-20th to l-10th part of sulphuric
acid.
The mode of operating is as follows: The vessel is partially
filled with water acidulated with sulphuric acid — 230 quarts of
water and 5 quarts of sulphuric acid being a convenient quantity.
About 15 Ibs. of the copper ore, previously calcined and reduced
to powder, is then stirred into the liquid in the vessel and allowed
to subside, after which the platinum frame is lowered on to the
surface of the ore, and the copper-lined bowl suspended in its
place, when the electric current immediately begins to act ; but it
is preferred to allow the ore to remain four or five days in the
acidulated water before applying the electric current. The liquid
during the process should be kept heated even as high as the boil-
ing point, by which the separation of the copper and its deposition
in the bowl will be facilitated. The time occupied in effecting this
is generally three or four days, when the whole of the copper is
removed. The acid liquid and sediment, which will contain any
other metals that may have been present, are run out through a
plug-hole in the bottom of the vessel. The sediment should be
tested to ascertain if it still contains any proportion of copper;
and if so, it can be mixed with fresh calcined ore and again oper-
ated on. The liquid does not require any fresh quantity of acid
to be added to it during the process, and afterwards it may again
be similarly used.
Here we have 20 pairs of plates recommended to be used in the
battery, making a destruction of 20 tons of zinc and acid for one
ton of copper, and taking four days to deposit. Twenty -one tons of
copper per week would be but a small quantity of copper made,
compared with smelting ; and at the ordinary per centage of ore
to get this, there will have to be operated upon 300 tons of ore,
requiring acres of tanks, heated according to specification, inde-
pendent of the furnace for calcining. Having got the ore calcined
and free of sulphur, it would be preferable to fuse it with car-
bonaceous matters and get the copper direct. Notwithstanding
the commercial absurdity of all these applications and patents, still
COATING WITH VARIOUS METALS. 627
there are several ingenious adaptations worthy of the attention of
the electro-metallurgist as a study in his profession.
DEPOSITION OF BRONZE. — The following solutions of different
metals are given by Brunei, Bisson, and Graugain, as being capable
of giving a deposit of bronze :
50 parts Carbonate of Potash,
2 " Chloride of Copper
4 " Sulphate of Zinc,
25 u Nitrate of Ammonia.
A bronze plate is used as the positive electrode/ The deposit
given by this solution has been seen by Becquerel, who mentions
that it bears comparison with any ordinary bronze ill appearance *
A solution of the above materials in water strikes the ear as some-
what hypothetical : that a mixed solution of copper and zinc will
give, under certain conditions, a compound deposit we know, and
also that, with a quantity of other salts present, will give peculiar
tints of color, a circumstance which may be obtained without a
compound deposit. But the difficulty to be overcome is to pro-
portion the deposit of different metals, so that we may make up a
solution and battery that will deposit either Mantz's yellow metal,
Stirling's yello\v metal, gun metal, or common brass, at pleasure ;
and that we may be able to produce compounds that are constant
and unvarying : so that, for example, we could deposit silver or
gold of the standard quality, all which, notwithstanding the many
statements that have been made in print, have yet to be discovered.
We have thus given a brief review of the practical operations
of Electro- Metallurgy for the guidance of the student, who as lie
proceeds, will find that the difficulties which at first beset his path,
will gradually disappear: easier modifications of processes will
suggest themselves, as all operators cannot with equal facility fol-
low the same directions. New facts will reveal themselves to his
inquiries ; a wide field of interesting and profitable research will
open up before his mind ; and the steady and persevering experi
menter and observer will not fail to reap an abundant harvest of
honor and gratification, in being an instrument in )romoting th<
knowledge of the working of the laws of Nature.
Progress of General Science, vol. ii.
628 THE PRACTICAL METAL- WORKER'S ASSISTANT.
CHAPTER XXXIII.
THEORETICAL OBSERVATIONS.
WE have described at considerable length, the practical details
connected with the art of electro-metallurgy, without pausing to
inquire into the philosophy of the action of the electric currents
by which the effects are produced. It will be unnecessary to enter
into a long discussion of the numerous theories that have been
advanced from time to time to explain the action that takes place
in a battery or decomposing cell, while the current is passing
through the solution — a brief reference to the more commonly
received opinions being sufficient for the present purpose.
ACTION OF SULPHATE OF COPPER ON IRON. — In' order to con-
vey our ideas accurately, let us suppose that the solution undergo-
ing decomposition is sulphate of copper. This salt is composed of
sulphuric acid and copper, which may be represented as S04-f Cu:
these are held together according to the law of chemical affinity ;
but if iron is put into the solution, the combination of the acid and
copper will be dissolved by the attraction of the acid to the iron,
for which it has a stronger affinity than for the copper. Hence
iron, put into sulphate of copper, decomposes it thus :
Cu, SO + Fe = Fe, SO4 + Cu.
"Were we to put a piece of copper into a solution of sulphate of
copper, there would be no action, the forces being equal ; but if
by any means we were to communicate to this piece of copper a
higher attractive force for the SO4 than that of the copper which is
already in union with it, we should cause the acid to leave the
copper it was originally combined with, and to combine with the
new piece of copper. Bearing these general principles in view, we
shall proceed to state the different opinions of authors on this
subject.
FARADAY'S THEORY OF ELECTROLYSIS. — Professor Faraday
says — " Passing to the consideration of electro-chemical decompo-
sition, it appears to me that the effect is produced by an internal
corpuscular action, excited according to the direction of the electric
current, and that it is due to a force either superadded to, or giving
direction to, the ordinary chemical affinity of the bodies present.
The body under decomposition (say sulphate of copper), may be
considered as a mass of acting particles, all those which are included
in the course of the electric current contributing to the final effect ;
and it is because the ordinary chemical affinity is relieved, weak-
ened, or partly neutralized by the influence of the electric current
in one direction parallel to the course of the latter, and strength-
ened or added to in the opposite direction, that the combining par-
ticles have a tendency to pass in opposite courses.
. " In this view the effect is considered as essentially dependent upon
THEORETICAL OBSERVATIONS. 629
the mutual chemical affinity of the particles of opposite kinds.
Particles aa could not be transferred or travel from one pole N,
towards the other pole P, unless they 5g9
found particles of the opposite kind,
bb, ready to pass in the contrary direc- /^~~\a t> «
tiori; for it is by virtue of their in- (*JP • °
creased affinity for those particles, com-
bined with their diminished affinity for such as are behind them
in their course, that they are urged forward.
" I conceive the effects to arise from forces which are internal,
relative to the matter under decomposition, and not external, as
they might be considered, if directly dependent upon the poles. I
suppose that the effects are due to a modification by the electric
current of the chemical affinity of the particles, through or by
which that current is passing, giving them the power of acting
more forcibly in one direction than in another, and consequently
making them travel by a series of successive decompositions, in
opposite directions, and finally causing their expulsion or exclu-
sion at the boundaries of the body under decomposition, in the
direction of the current, and that in larger or smaller quantities,
according as the current is more or less powerful."*
In the above figure, the particles aa may be termed copper Cu,
and the particles bb, sulphuric acid SO4, which will enable us to
follow the comparison of the different views.
GRAHAM'S THEORY OF ELECTROLYSIS. — Professor Graham sup-
poses that the compound particles, such as sulphate of copper,
possess polarity, so that the particles in the bat-
tery or decomposition cell will stand in rela- Fig- 590.
tion to each other in a polar chain, as in Fig.
590.
He then represents electrotyping by the
porous cell system, as follows :
" The liquids on either side of the porous division may also be
different, provided they have both a polar molecule. Thus, in
Fig. 591 the polar chain is composed of molecules of hydrochloric
acid, extending from the zinc to the porous division at a, and of
molecules of chloride of copper from a, to the copper plate. When
the Cl of molecdle 1 unites with zinc, the H of that molecule
unites with the Cl of molecule 2 (as indicated by the connecting
bracket below) ; the H of molecule 2 with the Cl of molecule 3 ;
the Cu of molecule 3 with the Cl of molecule 4 ; and the Cu. of
this laolecule being the last in the chain, is deposited upon the
copper plate. Dilute sulphuric acid in contact with an amalga-
mated zinc plate, and the same acid fluid saturated with sulphate
of copper in contact with the copper plate, are a combination of
fluids of most frequent application."f According to this theory
* Faraday's Experimental Researches, vol. i. paragraphs 518, 519, 524
f Graham's Elements of Chemistry, 2d edition, 1859.
630 THE PRACTICAL METAL-WORKER'S ASSISTANT.
all the particles between the zinc and copper during the action of
the batteries will be performing a whirling motion ; for, when the
Cl of molecule 1 is liberated, the H of 1 will combine the Cl of 2.
which compound molecule must whirl round to be in its propei
polar position, which will necessitate that interchange distinctly
referred to by Professor Faraday — a mutual transfer of the ele
ments ; the Cl will pass towards the zinc plate, and the H and Cu
towards the copper plate.
Fig. 591.
Zinc.
Copper.
DANIELL'S AND MILLER'S YIEWS. — Theories varying little from
these were held by the late Professor Daniell, till, by a series of
interesting experiments, in company with Professor Miller, he
found that there is no mutual transfer of the elements ; that the
negative element, or that represented above as Cl or SO4, is trans-
ferred from the copper to the zinc, or in a decomposition cell from
the negative electrode to the positive electrode : but the positive
element — that represented by H or Cu — is not transferred ; there-
fore, the theories of Professors Faraday and Graham are opposed
to a fundamental truth experimentally proved. Professors Daniell
and Miller conclude their paper, read before the Royal Society, by
the following observations :
" These facts are, we believe, irreconcilable with any of the mole-
cular hypotheses which have been hitherto imagined to account for
the phenomena of electrolysis, nor have we any more satisfactory
at present to substitute for them ; we shall therefore prefer leaving
them to the elucidation of further investigations to adding one
more to the already too numerous list of hasty generalizations."*
In this paper, the authors state that they found certain positive
elements transferred in small proportions ; thus, potassium 'from
sulphate of potash in J of an equivalent ; barium, from nitrate of
barytes, £ equivalent; and magnesia, from sulphate of magnesia,
TV equivalent. This was a difficulty for forming any theory, but
we have shown that this difficulty does not exist.
In all cases where two liquids are separated by a porous dia-
phragm, there is a mutual transfer of the liquids in distinct ratios,
according to time, either by what is called endosmosis, or by a dif-
fusion ; and the rate of transfer is materially affected by a galvanic
current passing through them. From observations and operations
made on a large scale, and from experiments on- various kinds of
* Philosophical Transactions, Part I. for 1844.
THEORETICAL OBSERVATIONS. 631
solutions, we believe that the fractional transfers of Professors
Daniell and Miller are the results of endosmosis or diffusion, and
not of electrolytic transfer. According to recent experiments by
Professor Graham, diffusion takes place in definite proportions.
We believe that no transfer of any base or positive element takes
place by electrolysis.
PROPOSED THEORY. — Having carefully considered the various
phenomena attending electrolysis, in the decomposition of metallic
salts, we think that the electricity is conducted through the solu-
tion by the base, or positive element, in the electrolyte, which it
does as if it was a solid chain of particles — or wire. We have
already said, that if to a solution of sulphate of copper we put a
piece of iron, the acid in union with the copper will leave it and
combine with the iron. If a piece of copper be put into the same
solution, no change will take place ; but if we by any means give
to this copper an increased tendency to unite with the acid, it will
attract the acid from the copper in solution by virtue of this in-
creased attraction. Suppose two wires coming from a battery are
Fig. 592.
placed in a solution of sulphate of copper, thus, (Fig. 592) : the
double row representing the compound atoms of sulphate of copper
forming the electrolyte : C C the copper or positive element, and
SO4 the sulphuric acid or negative element of the solution. The
two single rows C C, etc., at each end of the double row, represent
the wire or solid conductors of the electricity, from the battery to
the decomposition cell : the last particle of the single rows p n
nearest the double row may be viewed as the electrodes. The
sulphuric acid SO4, and the copper C, in solution, are held together
by their affinity for each other.
Now let it be supposed that an equivalent of electricity leaves
tk°. positive terminal of the battery P, and passes along the solid
particles of the conductor, that particle upon which the electricity
is, must be for the time in a higher state of excitement than the
other particles. When the electric current comes to the last par-
ticle of the solid chain p, which is in contact with the electrolyte,
its increased excitement causes it' to attract and combine with the
acid particle SO4 nearest it ; the electricity being dynamic, passes
632 THE PRACTICAL METAL-WORKER'S ASSISTANT.
to the first basic particle Cl, giving it an exalted excitement, which
causes it to unite with the acid particle SO4 2, the electric force
passing to C2, which becomes excited in turn, and takes the par
tides SO4 3 ; and so on through the chain till the last particle C5,
which, having no further acid to combine with, gives its electricity
to the solid conductor, or electrode n, and passes along to the bat-
tery, the particle C5 being thus left adhering to the solid chain of
particles, or electrode.
By this we observe that every equivalent of decomposition will
carry an equivalent of acid to the positive electrode, without taking
the metallic element to the other or opposite electrode. This is
exactly the fact of the case, the result that takes place in all solu-
tions undergoing decomposition by the current, and also in the
battery between the zinc and copper. In these explanations we
have spoken of electricity as a material substance, passing along
the line, being more easily conceived than the theory of vibra-
tions, etc. ; but the effects are the same, and we have seen no phe-
nomena in electric decomposition which are inconsistent with the
views here given.
APPENDIX.
THE MANUFACTURE OF RUSSIAN SHEET-IRON *
A PARTICULAR kind of sheet-iron is manufactured in Eussia,
which, so far as I know, has not been produced elsewhere. It
is remarkable for its smooth, glossy surface, which is dark
metallic gray, and not bluish gray, like that of common sheet-
iron. On bending it backwards and forwards with the fingers
no scale is separated, as is the case with sheet-iron manufactured
in the ordinary way by rolling; but on folding it closely, as
though it were paper, and unfolding it, small scales are detached
along the line of the fold.
In the following pages this kind of sheet-iron will be desig-
nated Eussian sheet-iron. This sheet-iron is in considerable
demand in Eussia for roofing, and in the United States, where
it is largely used in the construction of stoves and for encasing
locomotive engines. I am informed that it is there named
stove-pipe iron.
Eussian sheet-iron has been recently subjected to chemical
examination in the Metallurgical Laboratory of the Eoyal
School of Mines, and the analytical work has been executed
by my assistant, Mr. W. J. Ward. Portions of two sheets in
the collection of the Museum of Practical Geology have been
operated upon. These sheets differed considerably from each
other in thickness, and in the following account they will,
accordingly, be termed the thick and the thin sheets; the thick-
ness of the former was 0*019, and that of the latter 0*005 of an
inch.
The specific gravity of the thick sheet was 7*668, and that of
the thin sheet 7*645, at 16*67° C., or 62° F.
On digesting strips of the thick sheet in dilute hydrochloric
or sulphuric acid at a gentle heat, a tender, delicate black resi-
due, of the original form and size of the strips, was obtained.
This residue was examined microscopically, but not found to
exhibit any special structure. It disappeared almost wholly
when heated to redness with access of air, and consisted, for
the most part, of easily combustible carbon. The hydrogen
evolved by the action of dilute sulphuric acid upon strips of
the thick sheet was passed through a solution of acetate of lead,
when a minute quantity of black precipitate, consisting of sul-
* By JOHN PERCT, M D.
RrssrAN WEIGHT* AND MEASURES TJSED IN THE FOLLOWING PAGES. — Wtiyht*:—~[ Ib. Russian =
0 90264 Ib. avoirdupois ; 1 Pood = 361056 Ibs. avoirdupois. Measure :— 1 Archine = 28 Euglish
inches.
633
634 THE PRACTICAL METAL-WORKER'S ASSISTANT.
phide of lead, was observed. In operating upon 130 grains of
the sheet, no phosphoric acid was detected by the molybdic
acid test.
The proportions of carbon in the thick and the thin sheets
were ascertained by burning filings of the former and strips of
the latter in oxygen gas.
By the action of hydrochloric or dilute sulphuric acid, both
sheets yielded an insoluble residue, which contained silica,
oxide of iron, and chromium. The proportion of chromium
was found by fusing the insoluble residue with nitre, and sub-
sequently precipitating with nitrate of mercury.
ANALYTICAL RESULTS.
THICK SHEET. THIIT SHEET.
Per cent. Per cent.
Carbon* 0-060 0-305
Sulphur Trace None
Phosphorus None None
Manganese Not sought for 0*008
Copper {^'JSSiSK1"1} 0>025
Chromium 0'035
Ignited insoluble residue 0-047 0*108
Containing 0'035 of chromium. Containing 0*063 of silica.
The occurrence of the peculiar carbonaceous mass, left after
the solvent action of dilute hydrochloric or sulphuric acid, may
reasonably be accounted for by the method of manufacturing
Eussian sheet-iron, to be described in the sequel. The sheets
are interstratified with charcoal powder, and bound up in pack-
ets, each of which is subjected to repeated hammering. Hence,
it is easy to conceive how fine particles of charcoal should be
beaten in over both surfaces of each sheet ; and, if this be so, a
relatively larger proportion of carbon should exist in the thin
sheet, as is the case. Yet that some of the carbon is combined,
may be inferred from the fact that distinct hardening occurs
after heating the metal to redness and immersing it while hot in
water, and especially in mercury. (See Note at the end.)
In the volume on Iron and Steel, which I published in 1864,
I stated that the mode of manufacturing the Russian sheet-iron
in question was kept rigidly secret; that it was made from iron
smelted and worked throughout with charcoal as the fuel; that,
according to information which I had received from three inde-
pendent sources, the sheets, after the completion of the rolling,
were hammered in packets, with charcoal dust interposed be-
tween every sheet ; and that they were subsequently assorted,
and the outer ones, being inferior in quality, were thrown aside
as wasters (p. 730). Two of my informants were Tunner, of
Leoben, Styria, and Professor Styffe, of the Polytechnic Insti-
tution at Stockholm, when I had the pleasure 'of being associ-
ated with them on the Jury relating to Mining and Metallurgy
* Total carbon, inclusive of what is believed to be mechanically imbedded in the surface.
MANUFACTURE OF RUSSIAN SHEET-IRON. 635
of the International Exhibition in London in 1862. Beautiful
specimens of such Eussian sheet-iron were exhibited on that
occasion. My third informant was Mr. Septimus Beardmore,
Civil Engineer, who, at my request, has personally made inquiry
concerning the process of manufacture, and to whom I am
indebted for the following account, which he sent to me from
Eussia in 1866. The description of the process was communi-
cated to him by Mr. W. Yates, a mechanical engineer in charge
of an engine-manufactory at Nijni-Sergha, in the Oural. But
Mr. Beardmore, accompanied by Mr. Yates, had the opportunity
of inspecting the annealing furnaces, hammers, and other ma-
chinery at Michailovskoi, where the sheets are made from rolled
iron sent from the works at Kerchni-Sergha and Nijni-Sergha,
the latter supplying the puddled iron. As Mr. Beardmore
visited the works on the occasion of his passing through the
town on Sunday, when nothing was being done, he did not wit-
ness the manipulation.
I may add that I have the pleasure of including Mr. Beard-
more amongst the students who have attended the Metallurgical
Lectures at the Eoyal School of Mines.
DESCRIPTION OF THE MODE OF MANUFACTURE BY MR. SEPTIMUS
BEARDMORE.
This kind of sheet-iron is produced from the ordinary sheet-
iron, which is derived from malleable iron, obtained either by
puddling or by the Comtoise or Franche-Comte' process, termed
in Eussia the Kishni process. A detailed description of this
process will be found in my volume on Iron and Steel, above
referred to, at p. 602. Decarburization of the pig-iron is effected
in a charcoal-finery, by a particular method of manipulation ;
and the resulting ball is similar to that which is formed in the
charcoal-finery in common use in British tinplate works. There
is not much difference, it is asserted, in the quality of the iron
prepared in the Eussian works by puddling or by the Comtoise
process ; but the product of the latter is slightly preferred for
the manufacture of such sheet-iron as is now in question.
Sheets of ordinary sheet-iron are wetted with a brush and
dusted over with powdered charcoal. Eighty sheets so treated
are piled together, one upon the other in succession, and sub-
jected during three hours to a good red-heat in an annealing
furnace. The packet of sheets is then taken out of the furnace,
placed on rollers by means of a crane, and by the same means
brought under a hammer weighing 60 poods, or nearly 1 ton.
After having received sixty blows, equally distributed, the
packet is reheated and rehammered, the sheets being examined
to ascertain if any of them have become welded together. The
packet is a third time annealed, withdrawn from the furnace,
636 THE PRACTICAL METAL-WORKER'S ASSISTANT.
turned over, and hammered on the face now uppermost. It is
a.crain annealed, and hammered for the fourth and last time.
The sheets are sheared, assorted into Nos. 1, 2, 3, according to
their appearance, and again assorted according to weight, which
varies from 8 to 14 Ibs. per sheet. The dimensions of the sheets
are always (?) the same, namely, 4' 8" X 2' 4".
The price (in 1866)* of the sheet-iron manufactured in the
manner described is 2 roubles 50 kopecks per pood, or 25/.
(nearly $125) per ton. The payment is by piece-work, and the
men receive, per 100 sheets, 1 r. 25 k., of which the master gets
25 k., three under-masters 18 k. each, and the rest 15 k. each.
In addition to the cost of labor in the after and special part of
the manufacture, there are the costs for puddling and rolling,
which amount to 3J k. and 4J k. respectively.
Mr. Beardmore states that, on conversing with a Frenchman
from Bernadall's works, concerning the manufacture of this
kind of sheet-iron, he was informed that two hammers are used,
one weighing 40 poods and giving sixty blows a minute, and
the other weighing 60 poods and giving forty blows a minute;
that the former is employed first, and the latter afterwards, when
the packet of sheets " est bien dresse' ;" that the packet, con-
taining sixty sheets, is not turned ; and that the number of blows
to be given is left to the discretion of the master-workman.
But with respect to the mode of producing the characteristic
quality of these sheets, the Frenchman said, " C'est tout-a-fait
une affaire de poudre de charbon" — i. e. " it is wholly a matter
of charcoal-powder."
DESCRIPTION OF THE MODE OF MANUFACTURE BY PROF. PUMPELLY.
Pumpelly, Professor of Mining Engineering at Harvard
University, U.S.A., with whom I have the pleasure of being
personally acquainted, has recently published the following
description of the process, as he saw it practised at the works
belonging to the Demidoff family, situated at Nijni-Tagilsk, on
the eastern flank of the Oural Mountains: —
"Through the courtesy of Mr. Nietki, I was shown through
the works, and had an opportunity of seeing the process of
manufacture of the celebrated Russian sheet-iron, which has, I
believe, never been described. The magnetic ore is roasted at
the mine, in heaps of 10,000 or 15,000 tons, to remove the little
sulphur it contains. It is then smelted in charcoal blast-fur-
naces. After being puddled, the iron is rolled into plates about
2J feet long, 5 inches wide, and J inch thick. These, after
being heated in a furnace with a very reducing flame, are quickly
* With the Exchange at par; i. e. with the rouble worth 3s. Id., ten kopecks
per pood is about I/, (say $5) per ton. One rouble = 100 kopecks.
MANUFACTURE OF RUSSIAN SHEET-IRON. 6 LIT
brushed,, to remove any foreign substance that may have fallen
upon them, and are then passed between rolls, the upper one of
which is unconnected with the lower, rolling only by friction.
By the time the sheet is cooled, it is about 15 inches wide.
Packages of three sheets are now laid in the furnace, and then
rolled again, after the upper sheet has been brushed and char-
coal-powder thrown between them to prevent adhesion. If thin
iron is desired, the sheets are subjected to a third heating, in
packages of four or six, and rerolled, after which they are
trimmed to the proper dimensions. They are now sent to the
forge, where they are heated and hammered three times, in
packages of from sixty to eighty. After the first hammering,
each sheet is swabbed with a wet mop, to harden the surface
(it is said that tar is sometimes used for this purpose). Two
packages, one hot and one cold, are now mixed in alternate
sheets, to produce the greenish color in cooling, and the mixed
package is then passed backward and forward under a large
hammer, and, after this, is again mixed and rehammered. The
superiority of the Eussian product is due in great part to the
cleanliness of the work, and to the carefulness and skill of the
workmen. Every sheet that is at all spotted is thrown into the
second or third class, and the difference in value between these
and the first quality is deducted from the pay of the workmen.
The clippings of the sheets are worked up into fine iron, and
loss of material by the whole process is reduced to from 12 to
15 per cent. The fireproof bricks used in heating furnaces are
made from a fine quartz sand, which is merely sprinkled with
lime-water before being moulded and burned, a method of
making fire-bricks which might be useful, in many cases, to
our own metallurgists."*
The well-known Dinas bricks are composed of silica and
lime; and a description of the mode of manufacturing them
will be found in the first volume of my work on Metallurgy,
published in 1861.
DESCRIPTION OF THE MODE OF MANUFACTURE BY HERBERT BARRY.
The latest published account of the process of manufacturing
this kind of Russian sheet-iron in the Oural which I have met
with is that of Mr. Herbert Barry, and is as follows: —
" The refined iron is hammered under the tilt-hammer into
narrow slabs, calculated to produce a sheet of finished iron two
archines by one (56 inches by 28 inches), weighing, when
"Across America and Asia. Notes of a Five -.ears tourney around the
rid, a
npelh
:he se
Pp. 421.
638 THE PRACTICAL METAL- WORKERS ASSISTANT.
finished, from 6 to 12 Ibs. These slabs are called lalvanky.
They are put in the reheating furnaces, heated to a red-heat,
and rolled down in three operations to something like a sheet,
the rolls being screwed tighter as the surface sheet gets thinner.
This must be subsequently hammered, to reduce its thickness
and to receive the glance (i.e. polish or glaze). A number of
these sheets having been again heated to a red-heat, have char-
coal, pounded to as impalpable powder as possible, shaken
between them through the bottom of a linen bag. The pile,
then receiving a covering and a bottom in the shape of a sheet
of thicker iron, is placed under a heavy hammer; the bundle,
grasped with tongs by two men, is poked backwards and for-
wards by the gang, so that every part may be well hammered.
So soon as the redness goes off, they are finished, so far as this
part of the operation goes. So far, they have received some
of the glance, or necessary polish. They are again heated, and
treated differently — in this respect, that, instead of having the
powdered charcoal strewed between them, each two red-hot
sheets have a cold finished sheet put between them; they are
again hammered, and, after this process, are finished, as far as
thickness and glance goes. Thrown down separately to cool,
they are taken to the shears, placed on a frame of the regulation
size and trimmed. Each sheet is then weighed ; and, after being
thus assorted in weights, the sheets are finally sorted into first,
second, and third, according to their glance and freedom from
flaws and spots. A first-class sheet must be like a mirror, with-
out a spot upon it. One hundred poods of balvanky make
seventy poods of finished sheets ; but this allowance for waste
is far too large, and might easily be reduced. Four heats are
required to finish. The general weight per sheet is from 6 to
12 Ibs., the larger demand being from 10 to 11 Ibs.; but they
are made weighing as much as 30 Ibs., and may then almost be
called thin boiler-plates, being used for stoves, &c. Besides the
finished sheets, a quantity of what are called red sheets are made,
which are not polished, and do not undergo the last operation.
"Taking the Michailovskoi works, which are the largest
sheet-iron ones in the empire, I found that the power running
the sheet-rolls was equivalent to forty horses, the rolls making
seventy to eighty revolutions a minute. The hammers used
are powerful, having the surface of the stroke very large, just
the contrary shape there to the ordinary tilt-hammer. A gang
turns out in a shift from 450 to 500 sheets. In the central
works, where they make sheet-iron from puddled iron, they
roll it into the necessary size, and then roll this balvanlcy into
half-ready sheets, with the same sort of rolls as are used in the
north, but which, however, run much slower; 'the finish being
given also by hammers in the same manner, but leaving out
the final part of the operation of placing cold finished sheets
between the hot unfinished ones. The hammers are not so
MANUFACTURE OF RUSSIAN SHEET-IRON". 639
heavy, and the heating furnaces are not so well constructed and
do not regulate the flame so well. The trimming, sorting, &c.,
is carried out just in the same way. The waste is really greater
in the central works than it should be in the north, as the ham-
mered iron does not leave such a raw edge as the puddled. A
fact that proves the superior manufacture of the north over the
other parts of the empire is, that whereas in the former sheet-
iron is the best-paying, in the latter it is the worst business.
For the uses which sheet-iron is put to, ductibility is of the first
consequence; and no sheet-iron is of passable quality that will
not bend four times without breaking: some made in the Oural
I have bent as much as nine times without showing the break.
Coupled with this quality, the glance must be taken into con-
sideration, as good polished iron will not take so much paint as
the inferior polished.
" The most renowned trade mark in the world for sheet-iron
being lakovleff is by no means a proof that it is superior to that
of all other makers; and, in fact, it is not so. There are other
makers equally as good, and I find, beyond any doubt, that the
best sheet-iron in Russia is made at PastuchofFs works, a small
concern in the government of Yiatka ; and even at Michailov-
skoi I have seen sheet-iron equal in every respect to lakovleff' s.
For sheet-iron made from puddled iron, I assume the only large
makers to be the Vuicksa Works and Demidoff; and I much
prefer the manufacture of the former, as it is much softer."*
DESCRIPTION OF THE MODE OF MANUFACTURE, COMMUNICATED TO
THE AUTHOR BY N. DE KHANIKOF.
Towards the end of the last year (1870), I had the pleasure
of making the acquaintance of Mr. N. de Khanikof, an eminent
Russian man of science, while he was temporarily residing in
London, and I asked him whether he. could give me any infor-
mation concerning the manufacture of the kind of sheet-iron
here in question. In reply he stated that although he had a
personal interest in ironworks in Russia, yet he had no know-
ledge of the subject, but that he would communicate with a
friend who was engaged in its manufacture, and endeavor to
procure from him a trustworthy account of it. Shortly after-
wards I received a letter from Mr. N. cle Khanikof, dated Feb-
ruary 6th, 1871, enclosing the following description in German,
which he had obtained from Mr. Kokcharof. I have great
pleasure in publicly acknowledging my obligation to Mr. N. de
Khanikof for his kindness and promptness in this matter.
* "Russian Metallurgical Works, Iron, Copper, and Gold, concisely de-
scribed." By Herbert Barry, late Director of the Estates and Iron Works of
Yuicksa. London, 1870 ; pp. 29 et seq.
640 THE PRACTICAL METAL-WORKER'S ASSISTANT.
The manufacture of glazed sheet-iron is carried on at the
ironworks which are situated on both flanks of the Oural
Mountains. The sheets are derived from pig-iron smelted with
charcoal, and converted into malleable iron in a charcoal-finery.
The malleable iron is rolled into plates of an ordinary trade
size, namely two archines (56 inches English) long, and one
archine (28 inches) broad. At some ironworks it was attempted
to use puddled iron, but without success, as the sheets so ob-
tained did not possess the same soundness.
There is nothing particular in the rolling of the sheets, ex-
cept that it is conducted very carefully and quickly, so that a
gang of workmen in an ordinary shift of twelve hours will
turn out from 500 to 600 sheets.
The chief peculiarity of the Kussian method of manufactur-
ing sheet-iron consists in communicating to the surface of the
sheets by a particular process a mirror-like glaze of a brown
or smoke-gray color.
The rolled sheets are sheared and arranged in packets to the
number of fifty or sixty, and sometimes a hundred in each
packet, the surface of each sheet having been previously wetted
with water and dusted over with charcoal-powder. Each packet
is enclosed in waste sheets, and heated in an annealing furnace
during five or six hours, after which it is taken while hot to
the hammer ; and each sheet before cooling is freed as quickly
as possible from the remaining charcoal-powder. The sheets
are again arranged in packets, and hammered with, a particular
hammer, named in Kussian "razgonnyj moist." This hammer
weighs 60 poods (about 2166 Ibs. English), and gives from fifty
to sixty blows a minute; and its striking face is 14 inches wide
and 6 Inches long. Each packet is hammered uniformly over
its whole surface, and after cooling is annealed. After this
second heating, the packet is rehammered under the same ham-
mer during from ten to fifteen minutes, and is again annealed ;
and the annealing and hammering are again repeated from four
to five times. After the last annealing, the packet is hammered
during from twenty-five to thirty minutes under the so-called
glazing-hammer, which weighs from 40 to 50 poods (1444 to
1805 Ibs. English), and of which the striking face is from 16 to
17 inches long, and from 20 to 21 inches wide. After this last
operation the packet is opened, and the sheets are sheared for
the last time and assorted, according to weight and external
appearance.
The yearly production of this kind of sheet-iron in the Oural
is 1 J million of poods (about 24,182 tons English). The sheets
are usually two archines (56 inches) long and one archine (28
inches) wide, and weigh from 10 to 12 Ibs. Russian (1 Ib. Eus-
sian = 0*90264 Ib. avoirdupois).
Two articles have been published concerning this manufac-
ture in the Russian Mining Journal, one in vol. iii. 1835, and
MANUFACTUKE OF RUSSIAN SHEET-IRON. 641
the other in Nos. 3 and 4 of the year 1870. But I have not
had the opportunity of seeing either of those articles, which
are written in the Russian language.
DESCRIPTION OF THE MODE OF MANUFACTURE BY CAPTAIN N.
MESHTCHI.IUN.
Toward the end of the year 1866, 1 was favored with a letter
from a Russian mining engineer, Captain N. Meshtcherin, con-
taining a much more circumstantial and satisfactory description
of the mode of manufacturing the kind of sheet-iron which is
the subject of these pages than any of the foregoing, and than
any which, so far as I am aware, has hitherto been published.
The description is illustrated by hand-sketches and prefaced
with the following remarks, which I present with onlv a few
slight verbal alterations : —
"Sin: In your work, entitled 'Iron and Steel,' I noticed at p. 730, in the
article on Russian Sheets, your remark that ' the method of their manufacture
is,' you believe, ' kept rigidly secret, and the manufacture of such sheets is a
desideratum in this country.' Having, during about three years, been engaged
in Siberia as a mining engineer of the Russian Government, and having been
acquainted with that branch of iron industry, I thought that it would be of
some interest to you to have information concerning the methods of procedure
which are used in manufacturing such sheet-iron in Russia. The process is
freely open to the inspection of all foreign travellers, as well as to natives of
the country, but very little is known of it in Western Europe, chiefly because
foreigners are ignorant of the Russian language, and also on account of the
remoteness of the places of manufacture from Western Europe.
*****
" I beg to remain, yours, &c.,
" N. MESHTCHERIN,
" Russian Mining Engineer, Captain.
"68 Berners Street, Oxford Street, London,
Ibt/t November, 1866."
I may add that I had also the pleasure of making the author's
personal acquaintance.
The manufacture of sheet-iron in Russia is chiefly confined
to the ironworks on the eastern side of the Oural Mountains.
The malleable iron, which is the subject of this manufacture,
is derived from pig-iron, obtained by smelting the following
ores with charcoal in cold-blast furnaces — namely, magnetite,
carbonate of iron (sphaero siderite\ and red and brown hematite.
The conversion of the pig-iron into malleable iron is effected
either in the charcoal -finery or in the puddling furnace.
The puddle-balls, intended for the manufacture of sheet-iron,
are rolled into bars 5 inches wide and J inch thick. The iron
should be more crystalline than fibrous, and should contain
sufficient carbon to render it more like steel than iron. The
machinery required consists of one or two pairs of rolls and
two kinds of hammers. Reheating is conducted in furnaces of
41
642
THE PRACTICAL METAL-WORKER'S ASSISTANT.
particular construction. The rolls are driven by water-wheels,
and should make not fewer than fifty revolutions a minute.
The hammers are also put in motion by cams on the axles of
water-wheels. The hammer-heads are of wrought-iron, with
striking faces of steel. Each anvil consists of a solid block of
white cast-iron. It is necessary that the hammers and anvils
should be so made in order that they may have the requisite
hardness, in default of which the surfaces of the sheets would
not acquire sufficient brightness or polish. One kind of ham-
mer is used for widening, and the other for smoothing, the
sheets : both are raised to the height of 28 inches, and give
from thirty -five to forty blows a minute.
Fig. 594.
Fig. 593.
Fig. 593. Side elevation of the first kind of Hammer for widening the sheets, of the
Anvil, and of the Cam-wheel.
Fig. 594. End elevation of the Hammer-head and Anvil.
(The scale is given under Figs. 595 and 596. The numbers indicating dimensions are
English feet and inches.)
Fig. 596.
Fig. 595.
Fig. 595. Side elevation of the »econd kind of Hammer for smoothing the sheets, of
the Anvil, and of the Cam-wheel.
Fig. 596. End elevation of the Hammer-head and Anvil.
(The drawings for all the wood-cuts have been made by Mr. W. Prim.)
The reheating furnace is represented in Figs. 597-8-9-600,
and it is hoped that its construction will be clearly understood
from a careful examination of those figures. . Wood is the fuel
used. It will be perceived that this furnace differs widely from
the reheating or annealing furnaces employed in this country.
The fireplace extends under the bed of the reheating chamber
MANUFACTURE OF RUSSIAN SHEET-IRON".
643
from end to end, and the gaseous products of combustion enter
that chamber through a series of five similar and equal openings
in the bottom on each side.
Fig. 597.
Fig. 598.
Fig. 597. Longitudinal section of the Reheating Furnace on the line A B, Fig. 599.
Fig. 598. Horizontal section on the line E F, Fig. 597,
In the construction of these furnaces there is one principle
which must be rigidly observed, namely, the complete exclu-
sion, as far as practicable, of free atmospheric air from the re-
heating chamber, in order to prevent superficial oxidation of
the sheets. With this view, not only must the walls be made
impervious to air, but the fire and ash-pit doors (d d}, as well
as the end door (e), must be made to fit as tight as possible.
Tight fitting of the doors (d d) is secured by the arrangement
shown in the figures.
The puddle-bars, 5 inches wide and J inch thick, are cut into
THE PRACTICAL METAL- WORKER'S ASSISTANT.
pieces 29 inches lon.er, which weigh about 15-35 Ibs. avoirdupois
(10 Ibs.? — J. P.). These pieces are heated to redness and cross-
Fig. 599.
Fig. 600.
Fig. 599. Transverse section on the line C D, Fig. 597.
Fig. 600. End elevation, where the sheets are put in.
THE FOLLOWING LETTERS, WITH DESCRIPTIVE REMARKS, APPLY TO FIGS. 597-8-9-600.
a, Grnte.
bbbb, Flues leading from the fireplace into the reheating chamber.
r, Chimney, which, in the original sketches, is shown as made of riveted ironplnte.
d d, Fire and Ash-pit Doors: they are made of cast-iron, nnd are hinged at the top;
and to each door a hook is affixed, by which it may be conveniently opened.
e. Counterpoised Door.
/, Packet of Sheets, surrounded by logs of wood.
rolled into sheets about 29 inches square (see Fig. 601); and in
order to become thus extended, they require to be passed through
Fig. 601.
The shaded part represents a piece of puddle-bar cut for rolling, nnd 'be dotted lines the
form and dimensions of the resulting shccis.
the rolls about twelve or fourteen times. The sheets thus pro-
MANUFACTURE OF RUSSIAN SHEET-IRON.
645
duced are arranged in packets of three in each, heated to red-
ness, and rolled, each packet passing through the rolls about
ten times. But, just before rolling, the surface of each packet
is cleaned with a wet broom, usually made of the green leaves
of the silver-fir, and powdered charcoal is strewn between the
sheets, in the manner shown in Fig. 602.
Fig. 602.
Diagram, not to scale, showing the manner of strewing the charcoal-powder between the
pheets.
The sheets obtained from this rolling are sheared to the
dimensions of 28 inches by 56 inches. Each sheared sheet is
brushed all over with a mixture of birch charcoal-powder and
water, and then dried. The sheets, so coated with a thin layer
of charcoal-powder, are arranged in packets containing from
seventy to a hundred sheets each ; and each packet is bound
up in waste sheets, of which two are placed at the top and two
at the bottom, as shown in Fig. 603. A single packet at a time
Fig. 603.
Packet of sheet* bound up in waste sheets.
is reheated, with Logs of wood about 7 feet long placed round
it, as represented in Figs. 598, 599, the object of which is to
avoid, as far as possible, the presence of free oxygen in the re-
heating chamber. The gases and vapors evolved from heated
wood contain combustible matter which would tend to protect
the sheets from oxidation in the event of free oxygen finding
its way into the reheating chamber.
The packet is heated slowly during five or six hours, after
646
THE PRACTICAL METAL-WORKER'S ASSISTANT.
which it is taken out by means of large tongs and hammered
under the first kind of hammer (see Figs. 593, 594). The packet
is moved so that the blows fall in the order indicated in Fig. 604.
After this treatment, the surface of the packet presents a wavy
appearance, as the striking face of the hammer arid the face of
the anvil are both rather narrow. When the packet has tra-
velled about six times under the hammer, in the manner speci-
fied, from a to b (see Fig. 604), it is removed; and immediately
afterwards completely finished sheets are arranged alternately
between those of the packet. The packet thus composed, which.
Fig. 604.
Perspective view of a packet of sheets, showing the order in which the hlows of the
hammer are given.
contains from 140 to 200, or twice the number of sheets in the
packet subjected to the first hammering, is hammered under the
second kind of hammer (see Fig^. 595, 596,) in the same manner,
but not to the same extent, as the first packet. Instead of being
moved to and fro six times from right to left, it is moved so
only twice. By this treatment, if the hammering be carefully
executed, the sheets acquire a perfectly smooth surface; but
this result would not be obtained without the interposition of
the smooth-faced finished plates in the manner above described.
After the second hammering the packet is opened, the surface
of each sheet is again cleaned with a wet broom, and the sheets
are set separately in a vertical rack, in order to cool, as shown
Fig. 605.
Kack in which the second-hammered sheets are arranged.
MANUFACTURE OF RUSSIAN SHEET-IRON. 647
in Fig, 305, These sheets are next sheared to the dimensions of
28 inches by 56 inches.
The actual cost of manufacturing these Russian sheets is about
12£, 15,?, per ton, to which must be added general charges, which
raise the amount to 16£, or 171. per ton, exclusive of profit.
The average price of sheet-iron at the fair of Nijni-Novgorod
is about 22 f. or 251. per ton,
Although it must be admitted that not one of the foregoing
descriptions of the mode of manufacturing Russian sheet-iron
is complete in every respect, yet it is hoped that a careful and
comparative study of the whole will enable the manufacturer
of sheet-iron to obtain all the information, which he may desiro
on the subject. Details which have been omitted, even in the
most comprehensive of those descriptions, will be found in the
others,
If an attempt should be made to manufacture similar sheet-
iron in this country, it would, probably, not be necessary ex-
actly to imitate the Russian process in every particular. Thus,
instead of employing such an annealing furnace as has been
described, the method commonly pursued at tinplate works,
namely, annealing in covered cast-iron vessels, might be adopted.
NOTE,
Since the foregoing pages were in type, the following addi-
tional observations have been made: —
Strips of the thick and thin sheets were heated to redness in a current of
dry hydrogen, when steam, having a slight empyreumatic odor, was evolved
from the end of the glass-tube in which the experiment was made. By this
treatment the strips acquired the characteristic color and dull aspect of un-
polished iron. The surface of the thick plate, when magnified about fifty
diameters, was seen to be reticulated with minute cracks ; while here and there
were small pits, which contained black matter resembling charcoal. On one
or two of the strips raised lines, also reticulated, were observed, which were
doubtless the impression in relief of the cracks upon the sheet in contact with
which it had been hammered. The cracks seemed to penetrate to a certain
common depth, to which they opened on bending, leaving a central portion
free from cracks, as though the metal below the level of the cracks differed in
quality from that which was above it. The surface of the thin strips, which
had been exposed to the action of hydrogen in the manner described, was much
more finely granular and more uniform than that of the thick strips, and the
cracks were both fewer and smaller than those in the latter.
The production of steam by the action of hydrogen shows that the iron was
more or less superficially oxidized. The empyreumatic odor was probably due
to the presence of a little oily matter, as the strips experimented upon had not
been previously scoured or otherwise cleaned.
648 THE PRACTICAL METAL-WORKER'S ASSISTANT.
AMEEIOAS" SHEET-IEOl^.
THE manufacture of sheet-iron, although a branch of the
iron industry full of difficulties and peculiarities, has neverthe-
less been carried to a higher state of advancement in the United
States than anywhere else in the world save in Eussia.
Most of the sheet-iron used in this country is manufactured
in Pennsylvania, and from Pennsylvania iron. The greater
portion of the product is used for making stovepipe, while
some grades make a very close approach in finish and quality
to Russia iron. The latter are, however, manufactured as spe-
cialties under patented processes. So much superior is the
sheet-iron of the United States to that produced in England
that but small amounts of the foreign article are now imported
into the United States.
The prerequisites of a fine grade of sheet-iron are, charcoal
for fuel, clear iron for stock, a high oven, well-polished rolls,
and strong power. These being given, no difficulty need be
experienced. Both charcoal iron and puddled iron are used in
the manufacture of sheet-iron, but in any case the iron must be
reduced to the state of mill bars, and for fine sheets platines or
cuttings from merchant bars are preferred.
The machinery does not differ materially from that of the
ordinary rolling-mill, save that as the latter portion of the pro-
cess is conducted at a very low temperature of the metal, great
strength is required in the rolls and housings.
Common sheet-iron, from No. 15 to a higher number, is gene-
rally made from one thickness of bar run through the rolls in
single sheets at a cherry-red heat. At later heats two or three
sheets are rolled together. The effort is always to reduce the
iron as much as possible at the first heat, and the width of the
sheet is then determined. The iron, already in sheet-form, is
heated again, and the sheets in pairs or triplets rerolled : for
common thick iron, o~ for nail-plates, this comprises the extent
of the manipulation.
For polished iron additional heats are required, and the sheets
rolled by twos under hardened rolls, passing under a scraper to
remove the scale; or, in some establishments immersed in a
" pickle" of acid, which is not, however, necessary. If a very
high polish is required on thin iron, hard polished rolls must
be used and a high power, since the iron passes through the
rolls nearly cold. For this purpose machinery of extra strength
is demanded. The principal difficulty in the manufacture of
sheet-iron is to obtain the dark, metallic-gray color as nearly
as may be akin to that of Russia iron.
AMERICAN SHEET-IRON. 649
Impure iron will not make clear sheets, yet the brightest
colors are obtained from the whitest iron, which shows that the
quality of the iron does not affect the color. The fuel used has
much to do with the process. The presence of carbon, phos-
phorus, and silicon is advantageous; sulphur in the iron, or the
use of sulphurous coal, will produce a black muddled sheet.
An iron which scales freely will always be preferable for the
manufacture of sheet. The secret of making fine sheet-iron is
stated by practical workers to be its protection after the second
heat from the influence of sulphur, oxygen, and the silicious
dust of anthracite coal. This is done by high ovens, thus pre-
venting the flame from playing in the oven, and, if anthracite
coal be used, a low draft to avoid dust.
The imitations of Russia iron, of which several grades are
manufactured in the United States, while approximating in
color, rarely possess the other admirable qualities of that metal,
viz., malleability, and absence of a tendency to rust. The
most successful imitation is that manufactured by the firm of
Alan Wood & Co., of Philadelphia, which is of a superior
quality. The process under which this is manufactured is a
specialty of the firm, is covered by several patents, and is said
to be partially secret. In others of the numerous processes
used, the polish was attained by the use of oil in the later stages
of rolling. Sheets of beautiful appearance and peculiar malle-
ability have been produced by Marshall, Phillips & Co. of Phi-
ladelphia, during the current year. These were manufactured
also under a patented process, consisting in part, it is said, of a
peculiar method of pickling, and thus more perfectly scaling
the sheets.
A process for the manufacture of a grade of sheet-iron pos-
sessing all the lustre and malleability of Eussia iron, while it
resisted rust where Russia iron did not, is described by Prof.
Osborn,* whose account is here condensed : —
The sheets are of a thickness equal to No. 22. Equal parts,
by weight, of chalk, porcelain clay, and graphite, ground in
a paint mill to the consistency of molasses. Put the plates in
while still warm; withdraw them as soon as dipped, and put
aside to dry. When dry, pack eight to ten in a bundle ; heat
to dark red — continue rolling, and temper in annealing furnace.
Prepare three strong wooden boxes to receive plates edge-
wise.
Box 1. 1 part concentrated sulphuric acid, and 3 parts water.
Keep the sheets in until entirely free from scales. (Short time.)
Box 2, with lye. 1 part potash, diluted with 20 parts water,
and filtered. Plates remain till testing strip indicates greenish-
* The Metallurgy of Iron and Steel, Theoretical and Practical, in all its
branches ; with special reference to American Materials and Processes. 13y
H. S. Osborn, LL.D. 8vo. Philadelphia: Henry Carey Baird. 1869.
650 THE PRACTICAL METAL-WORKER'S ASSISTANT.
blue glossy tint; then remove them to box 3, with clear running
water — thoroughly wash the sheets.
Dry the plates by application of sawdust.
Put them in oven — vertically — two inches apart. Oven to
be heated with light, dry wood (hemlock or pine), and provided
with a crown of fire-bricks over the furnace, separating heating
chamber from furnace, and perforated with numerous small
holes for distribution from below. The fire is lighted after the
oven has been charged with plates to its full capacity. The
first result consists in the deposit of a light skin, or layer of
condensed smoke, over the entire surface of the plates. With
the increase of heat and the consumption of the smoke, this is
carried off, and the plates assume a bluish-black, glistening sur-
face. For the purpose of closely watching and controlling the
operation, one or more sides of the oven are provided with
suitable openings for the insertion of trying strips. A careful
examination of these testing strips will show the gradual pro-
duction of a carburet on the surface, which, at first, appears
scaly, and may be scraped off with a knife. Soon, however,
the carburet will be found to have embodied itself firmly with
the iron, and is no longer removable in the above manner.
From this period the heat must be checked, and the plates
allowed gradually to cool. When the plates are removed from
the oven, their surface will be very sensitive to the action of a
blow with a polished hammer, or to the pressure between pol-
ished rolls, such as are used for rolling out copper, silver, or
sheet-steel. The hammering is best accomplished by means of
a first, or fore hammer, and a polishing hammer, both of which
should be light-^— say, thirty to forty pounds.
After hammering, or rolling, temper. Tempering chamber
lined with plates of fire-bricks. Tightly closed to exclude air ;
fire kept up till heat of iron approaches the point at which it
changes from black to dark red. Opening for insertion of try-
ing strips. Be careful not to overheat the plates. Plates will
lose very little of the smoothness and polish — now ready for
market — but final 'treatment with light hammer, or polished
rolls, makes them better.
For a Silver-gray Tinge, — Immediately polish plates after
removal from water — and afterwards temper — like black; only
at the beginning of the tempering process inject small quantities
of rosin into the tempering chamber. This, by forming a heavy
layer of condensed smoke on the plates, much preserves their
former color, besides producing a lustrous surface.
MALLEABLE IRON CASTINGS. 651
MALLEABLE IRON CASTINGS*
" Malleable iron" is the term employed to designate those
castings, the brittleness of which has been partly or entirely
removed by the operation of " annealing," which consists in
burning off the whole or a part of the carbon combined with
the metal from which the castings were made.
Cast-iron, disregarding certain other substances combined %
with it, is essentially a compound of iron and carbon, in which
the carbon is partly combined with the metal, and partly mixed
with it; in the latter case, it is said to exist in the " graphitie
state."
Combined carbon, on account of its atomic state of division,
is more easily removed from the metal, either by the action
of oxidizing agents, such as metallic oxides, and the oxidizing
flame of a puddling furnace, &c., or by readily combining with
hydrogen and forming hydrocarbides, which we perceive when
we dissolve cast-iron in sulphuric or hydrochloric acid, for
instance. On the other hand, graphitic carbon is very hard
to burn, and requires the protracted action of oxidizing influ-
ences.
From the states in which carbon exists in cast-iron, this
metal has been classified into three principal subdivisions:
Gray metal, in which the light color is as it were concealed by
a multitude of graphitic laminae; White metal, where the car-
bon is in the combined state and unseen; Mottled cast iron, in
which most of the carbon is combined, whereas that in the
graphitic state gives to the metal the spotted appearance of
the trout. Gray metal is also called Foundry pig, and is gene-
rally preferred by the founders of ordinary castings, because it
retains its carbon and fusibility longer than the other kinds.
White metal is also called Forge pig, because it is preferred for
puddling, since it loses its carbon more readily than the gray
metal. The intermediate quality of mottled pig goes gene-
rally to the forge.
From what we have said about the two states in which car-
bon exists in cast-iron, and the greater facility of its removal
in one than in the other, we may rightly infer that white cast-
iron is to be preferred for malleable castings. Another reason
for doing so, is the appearance of the castings. Indeed, let us
suppose an article made of gray metal, rich in graphitic car-
bon; if, after a protracted heating in contact with oxidizing
* By A. A. FESQUET, Chemist and Engineer, Philadelphia.
652 THE PRACTICAL METAL-WORKER'S ASSISTANT.
substances we have succeeded in burning off the graphite, the
place it occupied in the metal will be empty, and the article
will be porous, and will show it. On the contrary, the article
cast from white metal, where the combined carbon is not visi-
ble, will appear with the same sharpness of shape and smooth-
ness of surface after, as before the annealing process.
Therefore, and provided the metal employed contains suffi-
cient combined carbon to insure the fluidity necessary for sharp
castings, white pig iron is to be preferred to gray metal for
the manufacture of "malleable iron'' castings, because the de-
carburization is more complete and rapid, the appearance more
pleasing, and the quality of the resulting metal better.
Carbon is removed from the cast-iron, by submitting it, at
a certain temperature, to the action of substances holding oxy
gen, and the resulting combination will be carbonic oxide very
possibly mixed with a certain proportion of carbonic acid. Air
will cause the carbon to burn, but its action is too energetic,
and is not well under control. The substances preferred for the
purpose are the magnetic scales of oxide of iron, produced by
blacksmiths and at rolling-mills, and iron ores or peroxides of
iron, which fulfil the requirements of cheapness, with regularity
and facility of working.
We must, however, remark that these oxides should be, as
far as practicable, free from silica and earths which, at the tem-
perature of the annealing furnace, will fuse and form a slag or
cinder, preventing the oxidizing action, especially if the cast-
ings should become coated with it. For this reason smithy
scales are preferred, although they contain less oxygen than
the ores; but the latter are with difficulty found entirely free
from the above fluxing impurities.
There is, up to a certain point, an analogy in the mode of
operation between cementing steel and annealing cast-iron.
In either case, the metals are submitted to a protracted heat
in air-tight vessels, filled with the reacting substances, and the
transformation takes place from the surface to the centre. But
here the similarity ceases; in one case the carbon of the char-
coal used penetrates the iron bar to form steel; in the other,
the oxygen of the surrounding oxide penetrates the cast-iron,
combines with its carbon, and escapes in the gaseous form.
It is easily understood that the thinner the casting, the more
rapid will be its transformation into malleable metal. Thicker
castings, if the heat has not been sufficiently high or protracted,
will exhibit in their fracture a kind of gamut of the gradua-
tion of the transformation. The external parts, which have
been thoroughly decarburized, are gray, easily filed and drilled,
and have lost their brittleness; and proceeding towards the
centre (which we suppose not to be decarburized), we see the
qualities of color, softness, &c., gradually diminishing, until
we find the previous white meial.
MALLEABLE IRON CASTINGS. 653
For some reason, not well understood, it would appear that
a temperature too high or prolonged, will hncen surfaces
already softened. Possibly, this may be due to a superficial
skin of magnetic oxide, hard and brittle, or to a coating of
fluxed impurities. At all events, castings not too thick, of a
good metal, and thoroughly decarburized, may be considered
chemically as iron without fibre, and a fibre may be imparted
to them by rolling or hammering. Indeed, we have seen such
malleable castings bent double, while cold, without breaking,
and without any previous condensation under the hammer.
Their ring, or sound, very nearly approximates to that of
wrought iron.
The manufacture of malleable iron castings is older than is
generally thought, although the knowledge of the true prin-
ciples on which it is based dates from the more recent period
of the establishment of chemical science. In his work on the
" Art of Converting Wrought Iron into Steel, and of Softening
Cast-iron" (Vart deconvertir le fer forge en acier^et Tart cPadoucir
lefer fondu\ published in 1722, Reaumur gives the numerous
experiments by which he succeeded in producing malleable
iron castings, which had already been made some twenty years
before, but in a secret manner.
At the epoch in which Reaumur lived, the true era of che-
mistry had not yet begun, the relations of carbon to iron in
pig metal were not known, and the various degrees of hardness
and appearance in cast-iron were attributed to the presence
of various impurities, sulphur especially. After many experi-
ments with all kinds of substances and salts — the results of
which were noted with a remarkable acuteness of observation
— Reaumur succeeded in his purpose with three different mix-
tures. Having observed that a plate of cast-iron, exposed for
a long time to the direct action of a fire, was covered with a
coat of black and red oxide, and that the metal underneath
had become softened (malleable), he collected such oxide for
the purpose of packing with it small bars of white cast-iron,
and after heating them in covered crucibles, he obtained a per-
fectly malleable iron (see page 472 of the above-named work).
His other mixtures were powdered limestone and charcoal, and
charcoal with calcined bone-dust. The first mixture is evi-
dently that used at the present time; the second may be ex-
plained by the oxidizing action, at a certain temperature of
the carbonic acid disengaged, which parts with an atom of oxy-
gen (CO2 -f C = 2 CO) combining with the carbon of the cast-
iron, and which becomes carbonic oxide. In the third case,
we may surmise that the carbon was burned out by the air of
the fire-place, penetrating through the interstices of the cast-
iron plates forming the boxes in which the metal and the mix-
ture were packed. The air was prevented from acting vio-
lently by the mass of bone-dust and powdered charcoal with
654: THE PKACT1CAL METAL WORKER'S ASSISTANT.
which the articles were surrounded. We do not believe that
the temperature was sufficiently high to decompose the bone-
dust, even in presence of the charcoal. The furnace employed
was of brick, and square, and divided by vertical partitions of
cast-iron plates, between two of which were packed the castings
and the mixture, and around which were flues for the circula-
tion of the gases of the fire-place.
However imperfect these dispositions may be. when com-
pared, with the present ones, Reaumur ascertained that oxides
of iron, and cast-iron, heated together in closed vessels, pro-
duced malleable iron; that for malleable castings, white is pre-
ferable to gray metal; that the castings, previous to annealing,
should be deprived of the adhering sand, which becoming
fluxed, prevented the reaction; that too protracted and too
intense a heat may harden the castings again; and that pro-
perly annealed articles may be bent, forged, welded, case-hard-
ened, and present all the properties and even appearance of
wrought iron.
After having explained the principles upon which the in-
dustry of malleable iron ca'sting is founded, and given a histori-
cal notice of the first trials made, we cannot do better than to
describe the actual processes, such as are applied at the Hard-
ware and Malleable Iron Works of Messrs. Ohas W. Carr, Jos.
S. Crawley, and Thos. Devlin, successors to E. Hall Ogden,
and whose store is at 307 Arch Street, Philadelphia.
In this large establishment, where everything is conducted
with the best order and understanding, anything in the line of
ordinary and malleable castings for building and cabinet, car-
riage and saddlery hardware, &o.f is made complete, from the
pattern to the casting, annealing, coppering, adjusting and
japanning of the articles. Indeed, the mechanical appliances
for finishing and adjusting different parts, comprise one of the
most interesting departments of the works, with their plan-
ing machines, lathes, punches, screw-cutting tools, grinding
and polishing stones, and drills which allow of the drilling of
several holes in the same piece at the same time, and at various
angles.
The pig iron used preferably for malleable castings is a
white charcoal pig, and is melted in cupolas, or in a rever-
beratory furnace (Fig. 606). This latter furnace, of which A
is the fire-place, B the hearth, 0 the tap-hole, D the flue to-
wards the stack, and E the door through which the impurities
are removed from the top of the molten metal, consumes more
fuel, and produces more waste than the cupola. On the other
hand, the metal is purer, because it is not melted in direct con-
tact with the fuel, and does not absorb its impurities, sulphur
especially. There is also the advantage that, should the metal
contain too much carbon, part of it may be removed by the
oxidizing action of the flame.
MALLEABLE IRON CASTINGS. 655
Most of the castings are made in green sand, from metallic
patterns, which insure a constancy of shape and of smooth
surfaces.
Fig. 606.
The castings, which are as brittle as glass, are then put into
" tumblers," which are revolving cylinders of cast-iron with
ribs inside, in which the articles are deprived of adhering sand,
and become polished by mutual friction.
The cleaned castings, intended for conversion into malleable
iron, are next packed close, with alternate layers of powdered
iron scales from rolling-mills, into rectangular cast-iron boxes
D (Fig. 607), which become of a rather elliptic shape, after a
certain length of use, and which can be placed one upon top of
the other, if need be, and closed at the top by a mixture of sand
and clay which prevents contact with the air, and follows the
settling of the mass.
Fig. 607.
Fig. 607 represents the disposition of the annealing furnace,
which resembles those employed for making the bone-black of
sugar refineries. A is the fire-place, B a flue conducting the
flame into the annealing chamber C ; and D D D are the cast-
iron boxes filled with the iron scales and the articles to be soft-
ened.
Leaving aside the time necessary for raising the temperature,
and the cooling off, the articles are subjected for about a week
656
to a white heat, not sufficient, however, to melt what may still
remain of cast-iron.
After a proper annealing, the castings are covered with a
film of oxide of iridescent colors — the yellow and azure blue
predominating — which resembles that kind of Champlain iron
ore called peacock, on account of its coloration.
Any adherent oxide is removed by another passage through
the "tumblers," and the process of malleable iron making is
finished. Any further grinding, polishing, boring, and adjust-
ing which may be needed, is made in the same works.
The oxide of iron, or scales, employed, have parted with a
portion of their oxygen during the annealing process, and the
loss is made good by grinding the scales, and rusting them
with a solution of sal ammoniac (hydrochlorate of ammonia).
It seems to us possible to do without the expense of sal ammo-
niac, by wetting the powdered scales several times with water,
stirring and drying them on the top of the annealing furnace.
Among the products manufactured by the above mentioned
firm, we have noticed hinges, entirely of cast-iron, and others
with wrought iron pivots; patent elastic washers for railroad
fish-plates, which prevent the nut from, unscrewing, and keep
it tight; castors for furniture, bolts, pulleys for cords of win-
dow sashes, keys, padlocks, screw presses, carriage parts, sad-
dlery hardware, &c. &c. In fact, it would be necessary to
make a catalogue with an index, of all of the patterns which
were shown to us.
It is difficult to state the cost of malleable iron castings,
since it depends to a great extent upon the size and the quan-
tity of the articles. We may say, however, that being given
a certain pattern, the malleable iron castings will cost from 70
to 80 per cent, more than ordinary castings from the same pat-
tern. This increase of price is necessitated by more labor,
the consumption of fuel for annealing, greater cost of pig
metal employed, &c. &c.
To sum up, malleable iron castings are useful, whenever
equal strength of material being not needed, the cost in labor,
if made of wrought iron, would be too great; or when a cast-
ing is needed without the brittleness of common cast-iron.
Scissors, sewing-machine parts, the butt-ends and guards, and
many other parts of gun locks, ornaments, &c. &c., are made
in quantities from malleable iron castings. Even nails, of all
sizes, are thus manufactured in England, and we are disposed
to believe that, if made of good metal and well annealed, they
may be at least equal to certain cut-nails produced from infe-
rior plate, and the fibre of which has been broken by the con-
cussion of the cutting machine.
Oxide of zinc has been proposed as a substitute for oxide
of iron, under the plea that the operation is more rapid.
A. A, FESyUET.
BESSEMEK STEEL. 657
BESSEMER STEEL.
IMPROVEMENTS IN THE PROCESS.
THE Bessemer process, as it was conducted several years
since, has already been completely described in this work. The
pig-metal still continues to be decarburized by the oxygen of
a powerful blast, but the appliances and mode of operation
have been modified.
It was thought, at the beginning, that it would be possible
to use any kind of pig-metal for the manufacture of Bessemer
steel, or homogeneous iron; and that the intense heat and blast
would be sufficient to volatilize the impurities of the metal,
L e., sulphur and phosphorus. There was, indeed, little basis
for this supposition in regard to sulphur, and not at all in re-
gard to phosphorus, since phosphoric acid is one of the least
volatile and most stable compounds known, and cannot be re-
moved from the iron except by powerful bases, such as potassa
and soda.
The doctoring by nitrate of soda, and other substances, has
been tried on a large scale; but all manufacturers prefer to
employ a pure pig-metal, comparatively free from sulphur and
phosphorus, and holding a certain percentage of carbon and
silicon, which are the two elements maintaining the combus-
tion inside of the converting vessel.
The raw metal which, up to the present time, best fulfils
the condition of purity with adaption to the Bessemer process,
is the English product known as Cumberland pig. There is,
however, little doubt that American pig-metal will be found
as suitable for the purpose, when the proper inquiry shall be
made.
The difficulty of producing a steel of the desired hardness,
that is, holding a certain proportion of carbon, by arresting
the blast at a certain period of the operation, has caused most
manufacturers to entirely decarburize the metal in the convert-
ing vessel, and then to recarburize it to the proper degree by
the addition of a proportion of Spiegeleisen calculated from the
amount of carbon in the latter metal. This method gives much
more certain results than by arresting the blast before entire
decarburization is accomplished, the proper time being then
guessed by fugitive differences in the color of the flame escap-
ing from the mouth of the converter.
Spiegeleisen (mirror iron) is a white pig-metal presenting
large facets in its fracture, and holding a variable proportion of
42
658
THE PRACTICAL METAL-WORKER'S ASSISTANT.
and carbon, the latter in the combined state.
Although nearly all of the manganese of this metal is found in
the slags, the small proportion remaining with the steel appears
greatly to improve its quality.
All of the trials made in various countries agree in this: that
to be successful the Bessemer process for making steel requires
a pig-metal of the first qual-ity, arid the addition of Spiegeleisen.
The shape and disposition of the apparatus have also been
modified, and we shall now examine these points.
The converting vessel or converter revolves on two trunnions
(Fig. 608) ; one of them is hollow and connected by a coupling
Fig. 608.
box with the blowing machine, the blast passing through a
Fig. 609
curved pipe along the lower part of the converter, and tcrmi-
BESSEMER STEEL. 659
nating in a metallic box beneath the apparatus. The other
bears a strong pinion to which a revolving motion is given by
a rack at the end of the piston rod of a double-acting water-
pressure engine.
The converter itself is an ellipsoidal vessel (Fig. 609), made of
strong wrought-iron plate. The upper and lower parts are
bolted together. On the top is an oblique mouth for receiving
the charge of metal, for the escape of gases, and the running out
of the steel. At the bottom, a metallic box receives the blast
and divides it through the tuyeres, five, six, or seven in num-
ber, and with five holes in each. The trunnions are fixed upon
a large wrought-iron belt, about midway of the apparatus.
The inside lining must be very carefully made; the refractory
clay, strongly beaten into it, is mixed with a certain quantity
of quartz, or ground firebrick free from scoriae.
The hole of the tuyere is also made of firebricks, with all of
the joints carefully luted. When the lining is dry a charcoal
fire is built in it, and all cracks are closed. Afterwards a
stronger fire is built, a certain blast is given, and the interior
receives a glazing of common salt.
The ashes being removed, the converter is placed in a hori-
zontal position, and the charge of pig-iron, previously smelted
in a cupola, is run into it by means of a trough lined with sand.
The charge is then level with the tuyeres, and the blast is turned
on before the converter is made to revolve to its vertical posi-
tion, which is slowly done. After fifteen to twenty minutes of
blast, and when the long and blue flame of oxide of carbon has
disappeared, the converter is swung again to a horizontal posi-
tion in order to receive the additional charge of five to ten per
cent, of Spiegeleisen. Having again been made to assume the
vertical position, after five minutes more of blast, the steel is
completed and run into a large ladle supportedi by a crane.
From this ladle the ingot moulds are filled.
The blast, after the introduction of the Spiegeleisen, is in-
tended to stir the mixture; but, as at the same time part of the
carbon is burned off, it is necessary to add more Spiegeleisen
than is needed for the desired per cent, of carbon in the steel.
At the Belgian works of Seraing, no blast is let on after the
introduction of the Spiegeleisen, and the mixture is considered
sufficiently intimate after the several pourings into the converter,
then into the casting ladle, and lastly into the ingots.
The steel poured into separate ingot moulds is apt to retain
a certain amount of slags, and to be porous. The ingots are
better when the moulds are in the form of siphons; the metal
is more condensed and without admixture of slags, since they
remain in the branch which receives the molten steel. These
moulds are generally disposed as follows: a metallic platform
is cast with deep grooves radiating from a centre, and the
grooves and bottom of the central part are lined with small
660 THE PRACTICAL METAL-WORKER'S ASSISTANT.
bricks of fire clay. The moulds are of heavy cast iron, and
present the shape of truncated quadrangular pyramids, the
larger sections of which rest upon the metallic platform. Now,
if we put one such mould over the central opening, and upon
each outlet of the radiating grooves, the metal poured into the
central mould will run into and fill the other moulds. All
the slag remains in the central mould which, on this account,
is a little higher than the others. When the steel has been
sufficiently cooled off, the moulds are lifted by a crane.
Before rolling the steel the ingots are reheated and their
cavities closed by condensing the metal under a steam hammer.
The converters are made to receive from three to ten tons of
molten pig-iron, which should, however, occupy but a small
place in them; the reaction and the boiling are so violent that a
part of the metal would be thrown out if there were not plenty
of room. A six ton converter is eleven feet high, and five and
a half feet in its widest diameter.
The oxidization of the silicon takes place before that of the
carbon, and but little flame is therefore seen at the beginning
of the operation. The silica unites with oxide of iron and forms
a small quantity of slag. The pressure of the blast, for medium
sized converters, is about fifteen pounds to the square inch.
The end of the decarburization is ascertained in different
means : by viewing the flame through an optical instrument
known as the spectroscope, which enables the observer to detect
a certain line in the spectrum or image of the flame, the dis-
appeartance of which line marks, to within a few seconds, the
conclusion of the process — by the sudden decrease of the long
blue flame, and its appearance when viewed with the naked eye,
or through different colored glasses superposed (blue and yellow),
giving a dark neutral tint. Through these glasses the flame
appears white as long as the decarburization is going on, and
turns red when all the carbon has been burnt off.
Notwithstanding the care taken to stop the blast at the pro-
per time, and to calculate the proportion of Spiegeleisen to be
added, the steel produced requires to be classified afterwards
according to its chemical composition and physical properties.
A small test ingot is cast at about the middle of the pouring,
and its fracture examined. After having taken from it the
necessary quantity of metal for the chemical determination of
the carbon, it is hammered, bent, hardened, and tempered, and
its tensile strength is also now and then ascertained. All of these
tests give valuable information, and permit of the classification
of the various grades of steel.
Nearly every steel works possesses its own mode of classifi-
cation, and we give below that used at the Belgian works of
Seraing, near Liege.
BESSEMER STEEL.
661
Number.
Hardness
and
Welda-
bility.
Tensile
strength.
Ton sper
eq. inch.
Permanent
elongation
per cent.
Per cent, of
carbon.
Designation.
Used for —
I.
a Does not 30£— 35£
20—25
up to 0.35
Extra soft
Guns, cannons,
harden ;
sheets, boiler
may be
plates, rivets,
welded
ropes
r6
Hardens
0.35—0.45
Soft
Machinery, axles,
and
tires, rails.
II. 4
welds
35f- 44
with
Medium
Tires, rails, piston
[c
difficulty
0.45—0.55
soft or
medium
rods, surfaces
subjected to
hard
friction.
'd
r
0.55—0.65
Hard
Large and me-
III. ]
Hardens
well and
does not
weld
44— 66£
5—10-
dium springs,
cutting tools,
files, saws, bits,
mining tools.
e
0.65 & over
Very hard
Fine springs and
tools, spindles,
&c.
INDEX.
Acid, nitric, for dipping, 593.
Acid, nitric, for dissolving- silver, 588.
Action of sulphate of copper upon
iron, 628.
Adhering of electrotypes to moulds,
prevention of, 502.
Advantages of cast-iron, 25.
Advantages of electro-plating, 605.
Advice to capitalists, by Smee, 554.
Air furnaces, 87.
Air furnaces, small construction of,
222.
Airo-hydrogen blow-pipe, 338, 350.
Air pumps, 88.
Alchemists, 43.
Alchemy, 18.
Alkalimeter test for cyanide of potas-
sium, 601.
Alkalies as fluxes, 43.
Alkalies, metals which form, have a
tendency to unite with those which
form acids, 29.
Alkali, preparation of, for removing
grease and oil, 579.
Alloy fusible for moulds, 540.
Alloy of silver, copper and iron, 592.
Alloy of the standard measure used by
government, 203.
^lloy of zinc and mercury, 556.
Alloys, 28, 144.
Alloys and their melting heats, 334.
Alloys, cohesion of, 214.
Alloys, deposition of, 622.
Alloys, experiments with, 226.
Alloys, fusibility of, 217.
Alloys, gold, 190.
Alloys, hardness, fracture and color
of, 210.
Alloys, hardness of, 30.
Alloys having specific gravity more
than the mean of their components,
207.
Alloys, having specific gravity less
than the mean of their components,
207.
Alloys, malleability and ductility of,
212,
Alloys, mixing, 222, 224.
Alloys more fusible than the individual
metals, 30.
Alloys most used, 179.
Alloys of copper and lead, 186.
Alloys of copper and tin, 185.
Alloys of copper and zinc, 183.
Alloys of copper, zinc? tin and lead,
187.
Alloys, remarks on characters of, 210.
Alloys, separation of the constituents
of, 31.
Alloys, silver, 199.
Alloys, solution for depositing, 622.
Alloys, weighing, 215.
Aluminium, 619.
Amalgamation, economy of zinc plates,
512.
Amalgamation, experiments upon the
economy of, 512.
Amalgamation, how often needful, 537.
Amalgamation, its advantages, 513.
Amalgamation of zinc for batteries.
511.
Amalgam, an, 29.
Analysis of black matter upon positive
electrode, 520.
Analysis of efflorescence, 536.
Analysis of refined iron, 72.
Analysis of steel and iron, 145.
Analysis of steel and iron, liegnault's
mode, 145.
Anchors, 88.
Ancient alloys of copper and tin, 185.
Angle and surface joints, 292.
Angular screw threads, 434.
Annealing of glass, 146.
Annealing of wire, 323.
Anodes anions of battery, 509.
Anti-attrition metal, Babbitt's, 203
Anti-friction cam-press, Dick's, 369
Anti-friction metal, Fenton's, 203.
Antimony, 28, 179, 180.
Antimony, curious phenomenon in tie-
positing of, 622.
Antimony, deposition of, 619.
Antimony, melting of, 221.
Anvils, hardening of, 154.
Apparatus, forms of, for electrotyping,
535.
Applications of coating with copper,563.
Arrangements for plating in factories,
594.
663
664
INDEX.
Arsenic, 28.
Arsenic, deposition of, 619.
Articles prepared for plating, how, 593.
Artificial and natural blasts, 50.
Atmospheric air, applications of, to fluid
metal, 69.
Atmospheric air, contact of iron with,
in purification, 21.
Atmospheric air, forcing, into the fluid
metal, 71.
Attraction of acids for metals, table of,
575.
Aurate of ammonia, 611.
Avoirdupois, table for converting de-
cimal proportions into divisions of
the pound, 216.
Axle of wheel carriages, known to
assume the crystalline state, 26.
Axletrees, hardening wrought iron, 158.
Babbitt's anti-attrition metal, 203.
Babington's battery, 517.
Ball and cross of St. Paul's Cathedral,
309.
Bright red heat, 96.
Ball, iron, 87.
Bank of England, Oldham's process of
annealing boxes containing steel
plates, 150.
Bar iron, manufacture of, 115.
Barron and Brothers' furnace, 229.
Batteries, of, 98.
Batteries, comparative constancy of
different kinds, 552.
Batteries, comparative produce, 553.
Batteries, comparative cost of, 554.
Batteries connected.against each other,
580.
Batteries, description of, 509.
Batteries, of different rnetals, 516.
Batteries, relative intensity of, 559.
Batteries, relative power of, 552.
Batteries, respective peculiarities of,
509.
Batteries, round, used for plating, 596.
Batteries, single pair, properties .of
metals fit for, 515.
Battery, Babington's, 517.
Battery, Bunsen's, 526.
Battery, Daniell's, 522.
Battery, depositing by separate, 550.
Battery, description of, 510.
Battery, formed by solution of silver,
600.
Battery, Grove's, 524.
Battery, single pair, 510.
Battery, single pair, different elements,
513.
Battery, single pair, distance between
plates, 513.
Battery, Smee's, 527.
Battery, solutions of, bow often changed,
537.
Battery, solutions, the comparative
value of, 536.
Battery, the earth, 529.
Battery, the first, 490.
Battery, use of, separate, 505.
Battery, Wollaston's common acid, de-
fects of, 519.
Battery, Wollaston's, 518.
Battery, Wollaston's, modification, 518.
Battery, process for making solutions,
589, 611.
Bawtree, Mr., 550.-
Beak irons, 287.
Bearings for locomotives, tin and pew-
ter, 235.
Belgian furnace, 41.
Belly helve, 112.
Bellows, 88.
Bellows for hand forging, 93.
Bells, casting, 267.
Bending thin metals, 288.
Berlin ornaments of iron, 275.
Bessemer's address to the British Asso-
ciation, 74.
Bessemer's apparatus, description of, 62.
Bessemer's experiments at Baxter
house, 126.
Bessemer's iron, analysis of, 71.
Bessemer's iron, fibrous stratum in,*73.
Bessemer's iron, test of, 73.
Bessemer's modification of steam ham-
mers, 70.
Bessemer's process, hammering and
squeesing in, 73.
Bessemer's iron, extreme tenacity of, 73.
Bessemer's iron, phosphorus in, 72.
Bessemer's process, change effected irl
iron by, 72.
Bessemer's process of refining iron, 22,
60.
Bessemer's process, removal of carbon
and silicon by, 72.
Bessemer's process to take advantage
of the impurities of iron uniting with
oxygen, 71.
Bessemer's squeezers, 69.
Besson's screw lathe, 443.
Best method of making silver solu-
tions, 589.
Binding screws, varieties of, 532.
Bismuth, 18, 28, 179, 181.
Bismuth, deposition of, 619.
Bits, drilling, 407.
Black leading non-metallic moulds, 505.
Black matter upan positive electrode,
520.
Black lead as a conductor, 505.
INDEX.
6t>0
Black red heat, 96.
Black appearance of gold pole, 614.
Blast, 88.
Blast, chain, 55.
Blast-furnaces, 44.
Blast machines, 52.
Blasts, natural and artificial, 50.
Blistered steel, 84.
Blistered steel welding, 139.
Bloom iron, 87.
Blowing apparatus, 52.
Blowing cylinder, effective power of, 52.
Blow-pipes in soldering, 335.
Bolts, 103-4.
Bolt screwing machine, 437.
Boiler-makers, shears for, 365.
Borax as a flux, 43.
Boring machines, 405.
Book covers electrotyped, 563.
Brace, French, 404.
Brads and nails, cut, 386.
Branson, Dr. F., on ferns and sea weeds,
541.
Brass, 225.
Brass and gun metal castings, pickling
of, 276.
Brass filings, loss in melting, 226.
Brass guns, moulding, 267.
Brass, ordinary yellow, 188.
Brass tubes for boilers of locomotives,
329.
Brass and copper, raised works in
sheet, 315.
Brass and copper soldering, 331.
Brass, depositing of. 624.
Braziers' hearth, 335.
Brick dust in moulding, 241.
Bright plating, how done, 603.
Britannia metal, 224.
Britannia metal, soldering, 334.
British mint, application of a wire-
drawing process in, 327.
Brittleness of metals, 208.
Broach, for philosophical instruments,
414.
Broach, Kinselaugh's, 414.
Broaches for gun barrels, 414.
Broaches for making taper holes, 413.
Bronze, deposition of, 627.
Bronze powder used as a conducting
medium, 504.
Bronzing, black, 573.
Bronzing, brown, 573.
Bronzing, green, 574.
Bronzing, varieties of, 572.
Bruce's type founding machine, 236.
Brugnatelli's experiments on deposi-
tion, 491.
Brushes for scratching plated goods,
593.
Bruns' battle of Arbello in relievo, 316
Brushing silver off copper goods, 597.
Building up or welding, 97.
Bullet moulds, 232.
Burnishing of plated and gilded goods.
593.
Busts and figures, how made, 548.
Button metals, soldering, 333.
Buttons, manufacture of, with a fly
press, 380.
Cadmium, 28.
Cadmium, depositing of, 519.
Cagniardelle, description of, 56.
Calcination and roasting, 36.
Calculating machine, axes or shafts for,
325.
Calico, covering iron rollers with cop-
per, 564.
Calico-printers' rollers, 564.
Calico-printers' rollers, etching of, 564.
Calico-printers, cylinders for, 253.
Calico-printing, plates of wire, 326.
Cannon, wrought iron for, 117.
Carbon in iron, 71.
Carbon and oxygen, union of, in Besse-
mer's process, 68.
Carbonates as fluxes, 43.
Carbonic acid gas, 47.
Carbonic oxide gas, 47.
Carburetted hydrogen gas, 47.
Case-hardening, 147.
Case-hardening, wrought and cast iron,
164.
Cast-iron, advantages of, 25.
Cast and wrought iron, difference in, 21.
Cast and wrought iron, hardening, 163.
Casting brass guns, 268.
Casting equestrian and other figures,
251.
Casting figures, 249.
Cast-steel, 84, 139.
Casting and founding, 230.
Castings, patterns for, iron, 261.
Catalan trompe, 54.
Catalan trompe, action of, 55.
Catalonia trompe, used in, 54.
Cathode, cations, 509.
Cave's punch improvement, 389.
Chain blast, 55.
Chain blast, construction of, 55.
Chain blast, air-chamber of, 55.
Chains, gilt, quantity of gold required,
617.
Chains, manufacture of, 381.
Chains, welding of, 136.
Chamfered drills, 395.
Chamfering of screw-taps, 423.
Change wheels for screws, calculations
of any combination of, 451
666
INDEX.
Change wheels for screw-catting, 449.
< harcoal, 46.
Charcoal iron, 20, 83.
Chased works in sheet metal, 315.
Chasing, the art of, 316.
Chasing tool, 453.
Chemical affinities, 39.
Chemical analysis, importance of, in
showing the composition of iron, 71.
Chemical combinations, liberate heat,
30.
Chemical part of metallurgy, 39.
Chemical vessels, coated with copper,
objections to, 568.
Chemistry, metallurgic, 17.
Chemistry in soldering, 331.
Chemistry, its aid in smelting, 42.
Chemistry, production and utilization
of metals allied with, 18.
Chemistry rests on a basis of metallur-
gic aspirations and empiricism, 18.
Chimney draught, sacrifice of fuel in,
51.
Chill castings, 256.
Chilled-iron castings, difficulties of
making, 163.
China sauce-pans lined by electrotype,
568.
Chisels, 139.
Chisels, hardening of, 153.
Chloride of silver dissolved in cyanide
of potassium, 589.
Chlorides, 39.
Chlorides, reduction of, 39.
Chlorous and zincous, proposed terms
for electrode, etc., 509.
Chronometer, balance springs, 156.
Chucking and reaming lathes, 469.
Circular saws, flattening, 320.
Circular works spun in the lathe, 300.
Cistern of Catalan trompe, 54.
Claims of originality made by experi-
menters, 506.
Clay coated with copper, 504.
Clays, process of refining, 59.
Classification of metals, 27.
Cleaning articles for plating, 593.
Cleaning of silver, 610.
Cleaning powders, 610.
Clocks, pinions of, 325.
Cloth, covered with copper, 563.
Coal, 46.
Coal-smelted iron inferior to charcoal
iron, 20.
Coal-smelted iron, sulphur and phos-
phorus in, 20.
Coating cloth, 563.
Coating cornice carvings, 563.
Coating glass and porcelain, 568.
Coating iron with copper, 574, 579.
Coating metals with nickel, 618.
Coating metals with palladium, 618.
Coating metals with platinum, 617.
Coating of figures with copper, 545.
Coating of flowers, 548.
Coating other metals upon cast-iron,
581.
Coating terra cotta, 563.
Cobalt, 28.
Coffee-pots of sheet metal, 310.
Cohesion of alloys, 214,
Cohesion of matter, 40.
Cohesive force, diminution of, 40.
Cohesive force of solid bodies, table of,
204.
Coin, discs of metal for, cut with fly-
press, 380.
Coin, how to make a copy of, 534.
Coke, 46.
Coke or charcoal preferable to coal for
steel, 148.
Cold, rolling of metals, when, 278.
Cold short iron, 82.
Coloring of gilding, 614.
Color of alloys, 210.
Combustible gases, utilization of, 48.
Combustion, 45.
Combustion of gas, 47.
Common acid batteries ; their defects,
519.
Comparative cost of different batteries,
554.
Comparative produce of different bat-
teries, 553.
Comparative value of common salt, sal
ammoniac, 537.
Comparative value of exciting solu-
tions, 517, 536.
Comparative value of sulphate of zinc
and sulphuric acid, 537.
Composition for taking casts in elastic
moulds, 549.
Compound cell process for electro-
typing, 556.
Conditions required in gilding, 612.
Conducting power of metals, 515.
Conducting power of solutions, 579.
Conduction, illustration of, 580.
Conduction of metals, effect of, in bat-
tery, 515.
Cone, the, in sheet metal, 283.
Constancy of batteries, experiments on,
552.
Constant battery, 523.
Converting vessel, Bessemer's, 63.
Converting vessel, Bessemer's, interior
of, 64.
Copper, 18, 28, 179, 181.
Copper and brass, raised works in
sheet, 315.
INDEX.
667
Copper and brass soldering. 331.
Copper and lead alloys, 186.
Copper and iron plates, experiment on
the power required to force a punch
through, 390.
Copper and tin alloys, ancient, 185.
Copper and tin, alloys of, 185.
Copper and zinc, alloys of, 183.
Copper and zinc, combination of, 225.
Copper and zinc when melted together
produce a high temperature, 30.
Copper cloth, 563.
Copper deposited on lead, 503.
Copper from ores by battery, 526.
Copper, fuel for forging, 94.
Copper, impurities in, used for elec-
trodes, 521.
Copper, melting of, 221.
Copper mould dissolved from silver,
607.
Copper mould, protection of, from
silver deposit, 607.
Copper moulds from plaster models, 544.
Copper, quantity deposited on square
foot of cloth, 563.
Copper soldering, 333.
Copper solutions for coating iron, 577.
Copper solutions, how made, 533.
Copper stereotypes, 504.
Copper, zinc, tin and lead alloys, 187.
Coppering an iron shaft, 580.
Copper-plate engraving, copying of,
568.
Copying copperplate engravings, 568.
Core-boxes, 246.
Cores for moulding. 241, 247.
Cored works, moulding, 245.
Coring, examples of, 247.
Cort's improvements in refining of iron,
20, 21, 22.
Cost of compound cell process, 556.
Cost of different batteries. 553.
Covering iron with zinc, 583.
Cracks and distortions in steel avoided
by proper manipulation, 151.
Crank forging, 120.
Crane, 110.
Creasing tool, 287.
Crook-bit tongs, 91.
Crucibles for cyanide of potassium, 576.
Crucibles for melting metals, 221.
Cruikshanks' battery, 517.
Crystalline structure of wrought-iron,
125.
Crystallization of iron, 116, 123.
Crystallization of iron, Mallet, on, 124.
Crystallizing tendency of wrought-iron
in large masses, 26.
Crystals of sulphate of copper on
electrodes, 562.
Cutter bars, 410.
Cutter stock, 439.
Cutters to assist the action of dies for
screws, 434.
Cutting of works in sheet metal, 286.
Cutting nippers for wires, 352.
Cyanide fumes, effects of breathin;
upon health, 615.
Cyanide of copper by adding cyanic'
of potassium to oxide of copper, 57
Cyanide of copper by adding cyanic
of potassium to sulphate of coppe
577.
Cyanide of copper from ferrocyanif
of copper, 578.
Cyanide of copper, modes of prepar:
tion, 577.
Cyanide of potassium, cost of man
facture, 576.
Cyanide of potassium, mode of pr
paring, 575.
Cyanide of potassium, impurities c
576.
Cyanide of potassium, precautions re-
quired in making, 576.
Cyanide of potassium, quantity for 100
ounces of silver, 589.
Cyanide of silver by dissolving chloride
of silver in Cy. K., 589.
Cyanide of silver by dissolving oxide
of silver in Cy. K., 588.
Cyanide of silver dissolved in yellow
prussiate of potash, 588.
Cyanide of silver, preparation of, 587.
Cyanide solution, decompositions, 597.
Cyanide solutions, peculiarity of, 578.
Cylinder, effective power of blowing,
52.
Cylinders in sheet metal, 282.
Cylindrical holes, broaches for, 414.
Cylindrical wire, 325.
Dalton, Dr., on the ductility and mal-
leability of metals, 279.
Daguerreotypes, electrotyping of, 550.
Damascus gun barrels, 135.
Daniell's and Miller's experiments on
Electrolysis, 630.
Daniell's battery, how constructed,
522.
Daniell's battery, properties of, 522.
Daniell's experiments on depositing,
492.
Daniell's nomenclature, 509.
Dannemora mines, Sweden, 83.
Davy, Sir Humphrey, 24.
Dead silvering upon medals, 609.
Deck beams of iron ships, 171.
Decks of iron ships, 171.
Decomposition cell, 524.
668
INDEX.
Decomposition effected by the battery,
490.
Decomposition effected by the pile,
490.
Decomposition of cyanide solutions,
597.
Decomposition of metallic sulphides
when heated without access of at-
mospheric air, 34.
Decomposition of plating1 solution, 597.
Deer's fut and suet, 545, 548.
Defects in batteries, 519.
Degrees of heat, 94.
De La Rive and Spencer's failure in
gilding, cause of, 575.
De la Rue, 494. 556.
Dented iron, 83.
Deposit, dissolving of, in solutions, 599.
Deposit, how to make, a non-metallic
mould, 545.
Deposit, how to prevent adhesion of,
534.
Deposit, non-adherence of, 581.
Deposit on battery coppers, 520.
Deposited metal, quantity of, depend-
ing on thickness of plaster, 499.
Depositing by separate battery, 550.
Depositing lead, iron and tin, 619.
Depositing silver, 607.
Deposition of alloys. 622.
Deposition of bronze, 627.
Deposition of metals on one another,
574.
Deposition of one metal on another,
491.
Deposition on other metals as coatings,
617.
Depositions in large moulds or objects,
547.
Dickerson's method of making wrought-
iron directly from the ores, 75.
Dick's anti-friction cam-press, 369.
Dies, hardening of, 154.
Dies, Holtzapffels', regulating for
screws, 487.
Dies for raised works in sheet metal,
311.
Dies for screws, 433.
Die stock, 436.
Die-stocks, 427.
Different densities, effects' of, 562.
Different densities of solution, 562, 598.
Different metals used for plating-, 603.
Dilations of metals by heat, 208.
Dipping articles in acid for plating, 593.
Dipping in nitrate of mercury, 593.
Dipping partially coated articles, 596.
Dirck's, Mr., notices of Jordan's claims,
496.
Discovery of electro-metallurgy, 492.
Discovery of electro-metallurgy, Smee's
opinion, 492.
Dissolving copper moulds from silver,
607.
Dissolving gold from gilt articles, 614.
Dissolving off deposited metal in solu-
tion, 559.
Dissolving silver from copper, 597.
Distance between battery plates. 513.
Distance, experiments upon, 513.
Distillation of mercury from zinc, 556.
Dividing engines, Ramsden's, 461.
Drawing down, 97, 102.
Drawing for glyphography, 564.
Drawing metal tubes, 327.
Draw plates for wire, 323.
Drawing wires, 322.
Drill of the Lowell machine shop, 390.
Drills, 392.
Drills, hardening of, 153.
Drills, methods of working, by hand
power, 397.
Drills for metals used by hand, 392.
Drill-stocks, 399.
Drilling and boring machines, 405.
Drop shot, new method of manufac-
turing, 276.
Drying articles from solution, 592.
Dry process for reduction of metallic
oxides, 32.
Dry sand moulds, 256.
Ductility and malleability of alloys,
212.
Ductility and malleability of metals,
Dr. Dalton on, 279.
Ductility of metals, 208.
Ductility of tin, 329.
Ductility, processes dependent on, 322.
Durability of iron ships, 178.
Early deposition of metals, 491.
Earth and Wollastou's battery com-
pared, 529.
Earth battery, properties of, 529.
Economy of amalgamating zincs, 512.
Economy of iron ships, 178.
Edges of plates in flattening, 320.
Effects of conducting power of solu-
tions and metals, 579.
Effects of conduction for a protection
coating, 586.
Effect of cyanogen on health, 615.
Effects of decomposition of cyanide
solutions, 598.
Effects of different densities of solu-
tions, 562, 598.
Effects of light upon silver solutions,
• 592.
Effects of resistance in batteries, 557.
Effects of size of electrodes. 595.
INDEX.
669
Efflorescence in porous cells, 536.
Elastic moulding, 544.
Elastic moulding, to make figures by,
549.
Elasticity of springs, cause of, 157.
Electric acid, 491.
Electricity from sandy deposits, 604.
Electricity from vats, 600.
Electricity viewed as an acid (electric
acid), 491.
Electrodes, crystals of sulphate of
copper upon, 562.
Electrodes, definition of, 509.
Electrodes, relative size and effects,
595.
Electrodes, size of, 552.
Electrodes, unequal action upon, 613.
Electro-decompositions, how affecting
the discovery of electro-metallurgy,
491.
Electro-decompositions, early opinions
of. 491.
Electro-gilding, 610.
Electro-gilding, objections to, 605.
Electro-metallurgy, first published de-
scription of, 493.
Electro-metallurgy, its discovery, 492.
Electro-metallurgy, Smee's opinion of
its discovery. 492.
Electro-metallurgy, works upon, 508.
Electro- metallurgy, name first applied,
508.
Electro-plating, solutions for, 587.
Electro-plating, advantages of, 605.
Electro-plating, objections to, 615.
Electro-plating, 587.
Electro relations of metals in different
solutions, 514.
Electrolysis, Daniell's theory of, 630.
Electrolysis, Faraday's theory of, 628.
Electrolysis, Graham's theory, 629.
Electrolysis, proposed theory of, 631.
Electrolyte, 510.
Electrotype processes, 533.
Electrotype, Spencer's first paper upon,
497.
Electrotypes from daguerreotypes,
550.
Electrotyping, forms of apparatus for,
535.
Electrotyping leaves and ferns, 541.
Elements, different, of batteries, 513.
Elements of electrolytes, non-transfer
of, 561.
Elkiugton's patent for silvering, 508.
Eisner upon galvanic soldering, 569.
Enamelling by galvanism, 571.
Encyclopedia Metropolitana on found
ing, 269.
Endosnaosis of solution, 630
Engineers' shearing tools, generally
worked by steam, 364.
English zinc oven, 42.
Engraved copper plates, copying ot,
568.
Engraving by galvanism, 494.
Engraving, Perkins's process for
transfer, 159, 161.
Equestrian figures, casting, 251.
Etching, experiments on, 500.
Evils of dipping articles partially
coated with silver, 596.
Exciting solutions for batteries, com-
parative value of, 536.
Experiments on galvanic soldering,
569.
Experiments upon distance, battery
plates, 513.
Expansion metal, 203.
Fairbairn's experiments on compara-
tive merits of wood and iron for
ship building, 177.
Fairbairn's experiments in iron ships
on canals, 167.
Fairbairn's experiments on joints for
iron ships, 174.
Fallacy of the compound -cell system,
556.
Faraday and Stoddart's discovery of
silver steel, 29.
Faraday's nomenclature, 509.
Faraday's report to Harbour of Refuge
Commissioners, 585.
Faraday's theory of electrolysis, 628.
Fenton's anti-friction metal, 203.
Ferrocyanide of copper to make solu-
tion, 578.
Ferns, how to copy, 541.
Figure casting, 249.
Figures and busts, how made, 548.
Figures, covering, with copper, 545.
Figures from elastic moulds, 549.
Figures, moulding of, 545.
File making, precautions against clink-
ing, 158.
Filling the moulds, 252.
Fire, 95.
Fire bricks, selection of, 109.
Fire, management of, 94.
First printed description of electro-
metallurgy, 494.
Flasks, iron founders', 254.
Flasks or casting-boxes, 240.
Flat-bit tongs, 90.
Flattening of thin plates of metal, 300.
Flattening saws, 319, 320
Flowers, coating of, 548.
Fluxing, 42.
Fluxes, 20, 42, 334.
670
INDEX.
Fly presses, punches used in, 377.
Forks and spoons plated by old pro-
cess, 605.
Forge for hand forging, 93.
Forge, pig iron, 82.
Forged tools, description of, 108.
Forged work subjected to welding
heat, 96.
Forging in large masses, deteriorating
effects of, 129.
Forging of iron and steel, 86.
Forging, ordinary practice of, 97.
Founding, 230.
Founding, Encyclopedia Metropolitana
on, 269.
Foundry moulds, 240.
Fourcroy, 491.
Fowling pieces, barrels for, 135.
Fracture of alloys, 210.
Frames and ribs of an iron ship. 170.
Francis's metallic life-boats, 295.
Franklin Institute, report on the Prince-
ton gun, 128.
Free oxygen required for the removal
of sulphur, 34.
French horn, bell of, 310.
Fuel for smith's forge, 94. •
Fullers, top,. 98.
Furnace, Belgian, 41.
Furnace, Dickerson's, 75.
Furnace, mercury distillation, 41.
Furnaces for melting metals, 220.
Furnaces for mixing metals, Barren's,
229.
Furnace, reverberating, 108.
Furnaces, 44.
Furnaces for gold and silver refining,
222.
Furnaces for soldering^ 335.
Fusee engines, 444.
Fusible metal moulds, 540.
Fusible metal moulds from plaster, 544.
Fusible metals, melting, 220.
Fusibility of alloys, 30, 217.
Fusibility of metals, 207.
Fusibility, relative, of metals, as a
means of classification, 28.
Galena, when heated without the ac-
cess of atmospheric air, suffers par-
tial decomposition, 34.
Galvanic action between the silver and
copper in dipping, 596.
Galvanic principles and rate of protec-
tion, 585.
Galvanic protection of metals, 579.
Galvanic protection, none in the air,
506.
Galvanic soldering, 569.
Galvanometers, 533.
Galvano-plastic niello, 571.
Gases, composition of, 47.
Gases, utilization of combustible, 48.
Gear cutting machine, 439.
German silver, depositing of, 624.
Gilding by mercury, 615.
Gilding, electro, 610.
Gilding electrotyped daguerreotypes,
550.
Gilding, how to regulate the color of,
614.
Gilding in 1805, Brugnatelli's experi-
ments, 491.
Gilding, practical suggestions on, 617.
Gilding, process of, 612.
Gilt articles, coloring of, 614.
Glass and porcelain, coating of, 568.
Glass and steel, analogy between, 146.
Glass, preparation of, for coating. 568.
Glyphography, 564.
Glyphography, instruction in, 566.
Gold, 28, 179, 189.
Gold alloys, 190.
Gold and platinum, 18.
Gold and silver, refining furnaces for,
222.
Gold, dissolving, from gilt articles,
614.
Gold leaf used as a conductor, 505.
Gold, melting of, 221.
Gold, preparing solution of, 611.
Gold, quantity necessary to deposit on
some articles, 617.
Gold, reduction of, by phosphorus, 548.
Gold soldering, 333.
Gold, strength of solution, how main-
tained, 613.
Gouges, hardening of, 153.
Government standard measure alloy,
203.
Graham's green bronze, 574.
Graham's, Prof., nomenclature, 509.
Graham's theory of electrolysis. 629.
Grandjean's lathe for screws (1729),
443.
Granthain on iron ships, 178.
Green sand moulds, 256.
Grove's battery, how constructed, 524.
Grove's battery, defects of, 526.
'Grove's battery, properties of. 525.
Guide-screw elements, practice in
originating, 466.
Gun barrels, broaches for, 414.
Gun, Mersey steel company's wrought-
iron, 129.
Gun metal, 188.
Gun metal castings, pickling of, 276.
Guns, brass, moulding, 267.
Gun lock springs fried in oil in tern
poring, 156.
INDEX.
671
Gutta percha moulds, 541.
Uutta percha used as a varnish, 568.
Gutta percha in the marine glue, 541.
Hammer hardened steel, 85.
Hammer, Nasmyth steam, 111, 112.
Hammer, works raised by the, 302.
Hammers, 99, 139.
Hammers for working wrought-iron in
large masses, 111.
Hammers, set, 98.
Hammers, tilt and trip, 143,
Hammer-tongs, 91.
Hammering, 100.
Hammering and squeezing of iron in
Bessemer's process, 73.
Hand forging, 88, 93.
Hardening and tempering, 144.
Hardening and tempering, common
examples of, 153.
Hardening and tempering steel, prac-
tice of, 147.
Hardening, less common examples of,
158.
Hardening, precautionary measures,
158.
Hardness of alloys, 210.
Hardness of metals, 208.
Hard hammering, crystallization from,
129.
Hard soldering, examples of, 339.
Hatchet stake, 287.
Hatchets, forging of, 138.
Heading tools, application of, 140.
Health, effects on, of breathing cyano-
gen fumes, 615.
Health, effects on, of the mercury gild-
ing, 615.
Healey's screw-cutter, 445.
Heat, black red, low red, bright red,
white welding, 96.
Heat, degrees of, 94.
Heat, deficiency of, preferable to an
excess of, in working steel, 149.
Heat, highest known, yielded by iron
blast furnaces, 44.
Heat, modes of applying, in soldering,
334, 335.
Heat, power of metals for conducting,
208.
Heated air, tendency of, 50.
Heating of iron and steel to soften and
make malleable, 95.
Heating of iron for rolling-mills, 118.
Heavy metals, classification of, 27.
Heavy metals, only, that the metallur-
gist has to do with, 27.
Heavy works in iron, 87.
Helix, 416.
Hemispheres of metal, 309
Hindley's screw, 427.
Historical anomaly relative to the
discovery of the art of electro-metal-
lurgy, 496.
History of metallurgy, 19.
History of the art of electro-metallurgv,
489.
Holtzapffel's screw cutting apparatus,
450.
Holtzapffel's taps, dies, hobs, and
screw tools, 485.
Hoop tongs, 91.
Hot blast, 88.
Hot short iron brittle when heated, 95
Hydraulic machines for cutting off
copper bolts, 368.
Hydraulic press in manufacturing lead
pipes, 330,
Hydrogen gas, 47.
Hydrostatic blast, 5o.
Hydrostatic presses, tubes of, 136.
Hyposulphite of silver solution, 590.
Hyposulphite of soda, preparation of,
591,
Illustration of conduction, 580.
Impurities in cyanide of potassium, 576,
Impurities in iron, 21, 77.
Impurities in iron, combination of, with
oxygen, at high temperatures, 71.
Impurities in sulphate of copper, 533.
Influences of galvanism in protecting
metals, 585,
Ingot hammering on a suage, 70.
Ingot moulds, preparation of, 69.
Inkstands, pewter, moulding, 233.
Instruction to amateurs in glyphogra-
phy, 566.
Intensity explained, 558.
Intensity tables of relative batteries,
559.
Iridium and platinum, 29.
Iron, 18, 28.
Iron, action with sulphate of copper,
575, 628.
Iron and copper plates, experiments
on the power required to force a
punch through, 390.
Iron and steel, analysis of, 145.
Iron and steel, forging of, 86.
Iron and wood for ship-building, 175.
Iron, application of, to ship-building,
167.
Iron, bar, manufacture of, 115.
Iron, bar, tensile strain of, varieties
of, 115.
Iron, bending of, 83.
Iron, Berlin ornaments of, 275.
Iron, Bessemer's, analysis of, 71.
Iron, Bessemer'?, phosphorus in, 72.
672
INDEX.
Iron bolts and nails coated and driven
into wood, 581.
Iron, brittle, 83.
Iron, carbon in, 71
Iron, case hardening, wrought and
cast, 164.
Iron, cast, coating with other metals,
581.
Iron castings, patterns for, 261.
Iron castings, pickling of, 276.
Iron, change effected in, by Bessemer's
process, 72.
Iron, charcoal, 83.
Iron, chemical pfocess of purification
of, 21.
Iron, chilled casting's, 163.
Iron-clad vessels, 179.
Iron coated with copper, 574.
Iron coated with platinum, 618.
Iron coated with zinc, 583.
Iron, coating of other metals with, 61 9.
Iron, combination of silica and other
earthy bases with, 69.
Iron, Cort's, Bessemer's, Plant's, and
Uchatius' improvements in refining,
22, 23, 24.
Iron, crystallization of, 116, 118, 123.
Iron, dented, 83.
Iron, effect of long exposure to the
heat, 117.
Iron, fibre of, 83.
Iron, fibrous, 125.
Iron for cannon, 116.
Iron for manufacture of steel, 83.
Iron for tin plating by Bessemer's
process, 73.
Iron founders' flasks, 254.*
Iron, fractures of, 83.
Iron, gilding of, 612.
Iron, hardening wrought and cast, 163.
Iron, heavy works in, 87.
Iron, " Hoop L," 83.
Iron, hot short, brittle when heated, 95.
Iron, impurities in, 21, 71.
Iron, low-moor, 116.
Iron, malleable, 77.
Iron, malleable castings, 164.
Iron, malleable, production of, 69.
Iron, melting and pouring, 269.
Iron, ocean steamers of, practical in-
formation on, 169.
Iron, oxides of, 33.
Iron, phosphorus in, 71.
Iron, piling of, in the furnace, 119.
Iron, pneumatically refined, by Besse-
mer, 73.
Iron, preparation of, for coating, 579.
Iron, pure, without puddling furnace,
69.
Iron, quality of, 83.
Iron, refined, analysis of. 72.
Iron, refining and working of, 75.
Iron rendered fusible by the presence
of carbon, 30.
Iron, scrap, 114.
Iron, selection of, 83.
Iron shaft covered with copper, 580.
Iron ships' decks, 171.
Iron ships, deterioration of joints of,
173.
Iron ships, durability of, 178.
Iron ships, economy of, 178.
Iron ships for sea-going purposes, early
example of, 167.
Iron ship, frames and ribs of, 170.
Iron ships, keels, 171.
Iron ships, riveting the plates of, 172.
Iron, silicon in, 71.
Iron, soldering, 334.
Iron solution for dissolving copper
from silver, 607.
Iron, stub, 83.
Iron, sulphur in, 71.
Iron, Swedish, 83.
Iron, tensil strength of, 117.
Iron vessels of war, 179.
Iron, welding of, 121.
Iron wire, assumes crystalline state,
26.
Iron wire drawn after coating, 581
Iron with antimony will cut glass, 31.
Iron worked at bright red and white
heats, 96:
Iron, works on, 86.
Iron, wrought, crystallizing tendency
in large masses, 26.
Iron, wrought, in large masses, 107.
Jacobi's experiments in decomposition,
493.
Jacobi's, Jordan's and Spencer's re-
spective claims to originality, 496.
Jelly moulds in sheet metal, 311.
Johnson and Airey's experiments on
the effects of iron ships upon the
ship's compasses, 169.
Joining of works in sheet metal, 278.
Joints, angle and surface, 292.
Joints for iron ships, Fairbairn's ex-
periments, 174.
Joints, form of, soldered, 332.
Joints of iron ships, deterioration of,
173.
Jordan's experiments on deposition,
493.
Jumping or setting up, 97, 102.
Keels of iron ships, 171.
Kind of solutions to be used for coat-
ing metals, 574.
INDEX.
673
Lace covered with copper, 563.
Lacquer for plaster moulds, 543.
Laminating rollers, use of, 279.
Lap-joints for iron ships, 173.
Large forgings, hollowness in, 127.
Large forgings require different treat-
ment according to shape and use,
120.
Large objects, deposition on, 547.
Lathes, circular works spun in the, 300.
Lathes for screws, 439, 440, 442.
Laws of deposition, 506.
Laws of deposition claimed by Smee,
507.
juaws relating to depositions pointed
out by Spencer, 500.
Laws to be observed in coating one
metal with another, 575.
Lead, 18, 28; 144, 179, 193.
Lead and copper alloys, 186.
Lead as an element in batteries, 515.
Lead, coating with, 619.
Lead, copper, zinc and tin alloys, 187.
Lead, gilding upon, 612.
Lead moulds from wood engravings,
503.
Lead moulds, how prepared, 503.
Lead soldering, 331, 333, 334.
Lead pipe, application of the hydraulic
press in manufacturing, 330.
Leather, depositing upon, for printing,
564.
Leupold's "Theatrum Machiuarum,"
429.
Lever drill, 403.
Life-boats, Francis's metallic, 295.
Lift-hammer, small, 92.
Light and heavy, classification of metals
as, 27.
Light, effects of, upon silver solutions,
592. v
Lines upon surface of deposited metal,
cause of, 561, 598.
Lithium, the lightest known solid in
all nature, 27.
Loam and sand for moulds, 240.
Loam moulds, 256.
Loam moulding, 264.
Locomotive wheels with hardened steel
tires, 162.
Loss of weight by dipping, 596.
Lowell machine shop, machines manu-
factured at, 388, 390, 391, 439, 469,
470.
Lowmoor iron, 116.
Low red heat, 96.
Machine for moving goods while being
plated, 599.
Magneto-electric machine, 530.
43
Magneto-electric machine, improved.
530.
Magnates, making off. 152.
Maintaining gold solution of proper
strength, 613.
Mallet, Mr., on wrought-iron in large
masses, 109.
Mallet on the crystallization of iron,
124.
Malleable iron, 69, 82.
Malleable iron castings, 164.
Malleable iron, manufacture of, 77.
Malleable iron, pure, 82.
Malleable iron, variefies of, 82.
Malleable metals, 144.
Malleability and ductility of alloys,
212.
Malleability of metals, 208, 278.
Management of fire, 94.
Management of the furnace, 222.
Mandrels, 143.
Mandrels for screws, 440.
Mandrel, old French, 440.
Manganese, 28.
Marine glue with gutta percha, 514.
Marteau frontal hammer, 111.
Martien's process of refining, 58.
Martien's process of refining iron, 24.
Mason's application of separate batterv,
505.
Materials for working wrought-iron in
large masses, 114.
Meal dust or flour in moulding, 241.
Medal, preparation of, for depositing
upon, 534.
Medals, dead, silvering of, 609.
Medals, their conducting powers as
affecting deposit, 580.
Melting and mixing metals, 220.
Melting and pouring iron, 269.
Melting heats of alloys, 334.
Mercury, 18, 28.
Mercury absorbed by zinc, 512.
Mercury dissolved in nitric acid, 593.
Mercury distillation furnace, 41.
Mercury, gilding by means of, 615.
Metal moulds, 547.
Mercury recovery from waste zincs,
512, 556.
Metallic life-boats, Francis's, 295.
Metallic moulds, 230.
Metallic ores defined, 17.
Metallic oxides, 31.
Metallic oxides, reduction of, 32.
Metallic sulphides, 33.
Metallic views, in the production of.
501.
Metallurgic chemistry, 17
Metallurgic operations, special, 39.
Metallurgy, history of, 19.
674
IXDEX.
Metallurgy, progress of, without prin-
ciples being understood, 18.
Metallurgy the source of chemistry,
18, 23.
Metals, patterns for moulding, 240.
Metal tubes, drawing, 327.
Metal, washing and cleansing, from
silica and other earthy bases, 69.
Metals alike in their affinities for
oxygen do not readily combine, 29-
Metals and alloys most commonly used,
179.
Metals and alloys, remarks on charac-
ters of, 210. '
Metals, bending of, 279.
Metals, brittleuess of, 208. ^
Metals, classification of, 127.
Metals, classification as light and
heavy, 27.
Metals, ductility of, 208.
Metals for founding, temperature of,
253.
Metals, fusibility of, 207.
Metals, gliding amongst the particles
of, 279.
Metals, hardness of, 208.
Metals having a strong tendency to
combine with oxygen, 28.
Metals, heavy, only that the metallur-
gist has to do with, 27.
Metals,. linear dilations by heat, 208.
Metals, malleability of, 208.
Metals, melting and mixing, 220.
Metals, power of, for conducting heat,
208.
Metals, properties of, fit for batteries,
515.
Metals, relative fusibility of, as a
means of classification, 28.
Metals requiring no flux in soldering,
334.
Metals, tabular view of the properties
of, 207.
Metals, tenacity of, 208.
Metals, thin elasticity of, 279.
Metals, the tendency of which to com
bine with oxygen is slight, 28.
Metals, useful, defined, 17.
Metals which form both acids and
bases by combination with oxygen
28. .
Metals whose oxygen compounds are
basic or have the property of bases
28.
Method of working cyanide of copper
solution, 578.
Millward's magneto machine, 530.
Mitchell's machine for motion, 598.
Mixing and melting metals, 220.
Mixture for coloring gold, 614.
Mode of suspending electrotypes, 560.
Models for moulding, 243.
VIodern copper and tin alloys, 185.
' Monkey," 89.
Monster gun, dimensions of, 123.
Monster gun, forging of, 122.
Mortises, 105.
Motion, machine for producing, 5'.)9.
Moulding cored works, 245.
Moulding, elastic, how made, 544.
Moulding, loam, 264.
Moulding of figures, 545.
Moulding simple objects, 238.
Moulds, 238.
Moulds, directions for making, 538.
Moulds, filling, 252.
Moulds in lead from wood engravings,
503.
Moulds in lead, how prepared, 503.
Moulds in plaster from plaster, 543.
Moulds, metallic, 230.
Moulds, non-metallic, prepared to re-
ceive deposits, 545.
Moulds of copper from plaster, 544.
Moulds of fusible alloys from plaster,
544.
Moulds of green sand, dry sand, and
loam, 256.
Moulds of plaster of Paris or sand,
236.
Moulds of wax, taken from plaster. 543.
Moulds, precautions necessary in pin-
ting them .into solutions, 547.
Moulds, preparation of wax for, 539.
Moulds, substances for making, 538.
Moulds to take in fusible metal, 540.
Moulds to take in gutta percha, 541.
Moulds to take in Plaster of Paris,
539.
Moulds to take in wax, 539.
Mounts, silver, how made, 604.
Murray's, Robert, discovery of the use
of plumbago, 505.
Music plates of wire, 326.
Music, printing of, 564.
Musket barrels, 134.
Nails and brads cut, 386.
Nasmyth's experiment with wrought
iron ordnance, 26.
Nasmyth's steam hammer, 111, 112.
Native alloys, 29.
Native printing, 542.
Natural and artificial blasts, 50.
Navy of the United States, greal
strength of, 179.
Needles, steel wire for, 323.
Negative pole, '509.
Newton's patent for coating cast-iron,
581.
INDEX.
675
Nasmyth's experiments, 125;
Nicholson's experiments, 491.
Nickel, 28, 178, 195.
Nickel, coating metals with, 618.
Nickel coating, use of, for gas pipes,
619.
Nippers for wires, 352.
Nitric acid for dipping (dippers' aqua-
fortis), 593.
Nitrogen, 47.
Noble metals, 17, 28, 32.
Nomenclature, 509.
Nomenclature, Daniell's, 509.
Nomenclature, Faraday's, 509.
Nomenclature, Graham's, 509.
Non-adherence of deposit, 581.
Non-metallic moulds, preparation of,
for deposits, 545.
Non-transfer of elements in electroly-
sis, 561.
Norway iron, 21.
Nuts,' 104, 477.
Nuts, elastic, 478.
Nuts, force exerted in bursting, 477.
Nuts of square thread, 478.
Objections to electro-gilding, 615.
Objections to electro-plating, 606.
Objections to silver articles made by
the battery, 608.
Observed facts, use of, 493.
Oil, tallow, wax, and resin in hardening
steel, 155.
Oldham's system of hardening rollers
for transferring impressions of steel
plates, 150.
Old method of gilding, 615.
Old method of plating, 604.
Oliver lift hammer, 92.
Opinions concerning electro-deposition,
491.
Opposite currents of electricity from
vats, 600.
Ordnance, wrought-iron, accident with,
in U. S. Navy, 25.
Ornaments, how made and applied to
old plate, 604.
Ostrander's improved machine for roll-
ing sheet metal pipe, 29
O'Tool's pin drill, 396.
Oven, English zinc, 42.
Overcoming resistance in solution, 557.
Oxyhydrogen blow pipe, 337.
Oxide as a solvent of earthy bases, 68.
Oxide, fluid, 69.
Oxide, fusion of, in Bessemer's process,
68.
Oxide of silver, 588.
Oxides, metallic, 31.
Oxides of iron, 33
Oxidizable metals, 225.
Oxidized silver, 609.
Oxygen, 28.
Oxygen, free, required for the removal
of sulphur, 34.
Oxygen, metals having a strong ten-
dency to combine with, 28.
Palladium, 179, 195.
Palladium and Platinum, 29.
Palladium, coating with, 618.
Palladiumizing process, 218.
Palmer's glyphography, 564.
Partitions in battery troughs, 519.
Patent for coating china and glass, 568.
Patent for depositing alloys, 623.
Patent for electro-magneto plating,
530.
Patent for extracting copper from ores,
625.
Patents for electro-metallurgy, 508.
Patterns, moulders', 243.
Patterns for iron castings, 251.
Patterns for moulding, 238.
Patterson, Dr.Thomas, 550.
Pattinson's crystallization process, 31.
Peat charcoal, 94.
Peat, Recce's process for smelting iron
with, 49.
Peculiarity in depositing copper from
cyanide solution, 578.
Pencil case, gold required to gild, 617.
Penknives, hardening of, 154.
Perkins' method of treating steel
plates, 147.
Pewter inkstands, moulding, 233.
Pewter moulding, 233.
Pewter soldering, 331, 334.
Philosophical instruments, broach for,
414.
Phosphorus in Bessemer's iron, 72.
Phosphorus in iron, 71.
Phosphorus solution for reducing gold
and silver, 548.
Pickling of iron, brass, and gun metal
castings, 276.
Pig iron, quantity of required for pro-
duction of malleable iron, 82.
Pile, chemical decomposition, 490.
Pinions of cloaks, 325.
Pinion wire, 325.
Pins, unannealed wires for, 324.
Pipe, machine for rolling sheet metal,
291.
Pipes, casting crooked, 267.
Pitch block for works in sheet metal.
315.
Pitch preparation for protecting cop-
per from deposit, 608.
Plant's process of refining iron, 23, 57.
676
INDEX.
Plaster of Paris, coated with copper,
504.
Plaster of Paris moulds, 236.
Plaster of Paris moulds, how taken,
539.
Plaster of Paris moulds taken from
plaster models, 543.
Plated metals, working of, 313.
Plates, riveting of, for iron ships, 172.
Plating, electro, 587.
Plating in large factories, 594.
Plating, metals best suited for, 603.
Plating, old method, 604.
Plating, practical instructions in, 594.
Plating solution, how prepared, 587.
Platinum, 28, 179, 196.
Platinum as an element in batteries,
515.
Platinum, coating with, 617.
Platinum, nitro-muriate, 527.
Platinum, solutions of, 617.
Platinizing silver, 527.
Platinode, 509.
Pliers, 91.
Plumbago as a conducting medium
discovered, 505.
Plumbers' ladle, 220.
Poles, positive and negative, defined,
509.
Polygonal figures in sheet metal, 282.
Porcelain covered with copper, 568.
Porous cell, depositions in, 523.
Porous cells, how preserved, 523.
Porous vessel and diaphragm, 535.
Portable hand drill, 469.
Position of electrotypes in solutions,
560.
Positive pole, 509.
Potash, prussiate of, use of, in case
hardening, 166.
Potash, sulphite, how prepared, 591.
Potassium, cyanide of, mode and cost
of preparing, 576.
Pot metal, 189.
Pouring iron, 269.
Practical instructions in plating, 594.
Practical objections to solid deposit,
607.
Practical suggestions on gilding, 617.
Precautions on putting moulds into
solution, 547.
Preparation of articles for plating,
593.
Preparation of glyphotypes, 564.
Preparation of non-metallic moulds for
receiving deposit, 545.
Preparation, silver, 587.
Preparation of solutions of gold, 610.
Preparation of transfer paper, 567.
Preventing electrotypes adhering, 502.
Princeton, wrought-iron gun, 128.
Principles of galvanic protection, 579.
Principles on which metallurgie pro-
cesses are based, 39.
Printers' type, metals for, 224.
Printing by electrotypes, 564.
Printing by electrotype plates pro-
posed by Spencer, 499, 503.
Printing by glyphography, 566.
Printing, difficulty experienced in pre-
paring plates for, 499.
Printing of leather by electrotypes,
564.
Prismatic vessels in <*heet metal, 282.
Process of gilding, 612.
Processes dependent on ductility, 322.
Production of a purer iron by the ap-
plication of atmospheric air to the
fluid metal, 69.
Properties of metals fit for batteries,
515.
Properties of metals, tabular view of
the, 207.
Protection of silver coating, 593.
Protection of silver surface, 609.
Prussiate of potash, use of, in case
hardening, 166.
Puddled iron preferable to scrap iron
for forging, 118.
Puddlers' balls, Winslow's machine
for compressing and rolling, 77.
Puddling, 77.
Punches, 143, 370.
Punching and shearing machine, 366.
Punches used in fly presses and their
products, 377.
Punches used without guides, 370.
Punches used with simple guides,
374.
Punching, 104.
Punching machinery used by engineers,
388.
Pure iron will bear a great degree of
heat, 95.
Pyrites, iron, melt at a low red heat,
34.
Quality of magneto-machines. 523.
Quality of metal regulated by battery,
594.
Quantity of cyanide of potassium to
precipitate 100 ounces of silver, 589.
Quantity of metals deposited, how
known, 596.
Quantity of nitric acid to dissolve 100
ounces of silver, 588.
Railway axles, crystallization of, 26.
liaised works in sheet metal, ornament-
al, details of, 310.
INDEX.
677
Raised works in sheet metal, peculiar
methods in working, 313.
Ramsden's apparatus for originating
screws, 462.
Eamsden's dividing-engine (1777), 461.
Rate of depositing silver, 603.
Razors, hardening of, 154.
Recently-patented refining processes,
57.
Recovery of gold from solution, 615.
Recovery of silver from solution, 592.
Red short iron, 82.
Recce's patent for conversion of peat
by distillation, 49.
Refined iron, analysis of, 72.
Refining and working of iron, 75.
Refining processes, 22.
Refining processes, recently patented,
57.
Refining vessel, Bessemer's, 62.
Regulating the color of gilding, 614.
Relative intensity of batteries, 559.
Relative power of batteries, 552.
Relief, sheet works in high, 315.
Removing of grease or oil from metals,
579.
Reptiles, moulding of, 542.
Resistance, effects on deposits, 551,
557.
Reverberatory furnace, 108.
Reverberatory furnace employed in
Oldham's process of annealing boxes
of steel engravings, 159.
Reversing and figure casting, 249.
Rhodium, 179, 198.
Rhodium and platinum, 29.
Ribs and frames of an iron ship, 170.
Riveting of plates of iron ships, 172.
Riveting, set, 287.
Roasting and calcination, 36.
Rollers of iron-works, 80.
Rollers for printing, 564.
Rosin and wax moulds, 539.
Rotary shears for metal, 368.
Russian iron, 21, 115.
St. Paul's Cathedral, bell and cross of,
309.
Sal ammoniac, solution of, for batter-
ies, 537.
Salts of cyanide of copper and potas-
sium, 576.
Salts, which are important in metallur-
gy, 39.
Salt, solution of, for batteries, 491.
Sand moulds, 236, 237.
Sand moulds, iron founders', 254.
Sand sprinkled upon iron, 96.
Sand used for scouring, 593.
Sandy deposit, 534.
Sandy deposit, electricity from, 604.
Saws and springs lose their elasticity,
by grinding and polishing, 156.
Saws, flattening, 319.
Saws, hardening of, 155.
Scales on steel should be ground off
before hardening, 152.
Scissors and shears for soft, flexible
materials, 354.
Scoriae* and metal, mixture of, by vio-
lent ebullition, 69.
Scrap iron, 114.
Scrap iron generally used in forging,
119.
Scrap iron, necessity of cleansing, 119.
Scrap iron not desirable for forging,
118.
Scrap iron, various qualities in, 118.
Scratch brushes, 593.
Screw, cohesive strength of the hold,
474.
Screw-cutter, 445.
Screw-cutter bar, 426.
Screw-cutter, Healey's, 445.
Screw-cutting in lathes with traversing
lathes, 440, 442.
Screw-cutting tools, 416.
Screw, elementary idea of, 416.
Screw, helical ridge of the external,
471.
Screw-lathe, earliest, (1569), 443.
Screw, left-handed, 435.
Screw-mandrel lathe,. 441.
Screw-plates, 427.
Screw-plate, thickness of the, 428.
Screw-shaft forging, 120.
Screw-stocks, 435.
Screw-tangent, 427.
Screw-tap, O'Neal's, 422.
Screw-tap, original, 427.
Screw-taps, angle for, 421.
Screw-taps, chamfering, 423.
Screw-taps, cylindrical, 426.
Screw-taps, half-round, 421.
Screw-taps, use of, 425.
Screw, the cohesive strength of the
bolt, 473.
Screw-thread, mechanical power of,
473.
Screw-threads, approximate values of
Holtzapffel's, 485.
Screw-threads, considered in respect
to their proportions, form and gen-
eral characters, 470.
Screw-threads, square and angular, 434.
Screw-tool cutter or hob, 427.
Screw-tools for angular threads, 453.
Screw-tools for square threads, 453.
Screws, accuracy of, 461.
Screws, angular cutting, 452.
678
INDEX.
Screws for astronomical purposes, ap-
paratus for originating, 419.
Screws, apparatus for cutting original,
by means of a wedge or inclined
plane (1763), 459.
Screws, binding or attachment, 416.
Screws, change-wheels for, 449.
Screws, common, 419.
Screws cut by hand in the common
lathe, 439.
Screws, cutting internal with screw-
taps, 420.
Screws, dies for, 433.
Screws, diversity of, 416.
Screws, double, triple, and quadruple,
416.
Screws, early contrivances for cutting,
428.
Screws, hollow, 417.
Screws, internal square threads, 455.
Screws, large master- tap for, 432.
Screws, long, 433.
Screws, making small, 428.
Screws, measures and relative strength
of, 472.
Screws, medium master-tap for, 432.
Screws, nuts of coarse, 481.
Screws of exact value, 463.
Screws, originating, 418.
Screws, regulating, 416.
Screws, Reid's machine for cutting,
460.
Screws, small master-tap for, 432.
Screws, table for angular thread, 483.
Screws, table for small, of five angular
threads, 484.
Screws, tangent, 481.
Screws, the use of the inclined knife in
cutting, 463.
Screws, threads of, 419.
Screws, uniform system of threads, 483.
Screws, various modes of originating
and improving, 457.
Screws, Walsh's cutter for, 419.
Screwing bolts in the lathe, apparatus
for, 456.
Sea-weeds, how to copy, 541.
Silicium, 619.
Set-hammers, 98.
Set off, to make, 101.
Shaping-machine, 439.
Shaw's manual of electro-metallurgy,
508.
Shears, 352.
Shears for metal, worked by manual
power, 360.
Shear steel, 84, 139.
Shear steel bears the highest degree of
heat, 95.
Sheet-metal, hammers used in, 287.
Sheet-metal pipe, improved machine
for rolling, 291.
Sheet-metal, polygonal figures in, 282.
Sheet-metal, tools used in working, 286.
Sheet-metal, works in, made by cutting,
bending and joining, 281.
Sheet-metal, works in, made by joining,
278.
Sheet-metal, works in, made by raisin?,
300.
Ship-building, application of iron to,
167.
Ships, sheathing of, how destroyed, 586.
Shot-moulding, 232.
Shutting together in welding, 131.
Silica, 42.
Silicon in iron, 71.
Silver, 28, 179, 198.
Silver alloys, 199.
Silver and gold, fuel for forging, 94.
Silver and gold, refining, 222.
Silver articles made by battery, 607.
Silver, chloride of, dissolved in cyanide
of potassium, 587.
Silver, cleaning of, 610.
Silver, curious alloy of, 592.
Silvering, dead, upon metals. 609.
Silver dissolved in acids, 587, 588.
Silver, hardness of, effected by battery
594.
Silver, hyposulphite solution, 590.
Silver, made by electrotype, objections
to, 608.
Silver, melting of, 221.
Silver mounts in the old process, 604.
Silver, oxide of, dissolved in cyanide of
potassium, 588.
Silver, platinizing, 527.
Silver, protection of, in air, 609.
Silver, recovered from solutions, 592.
Silver salts, reduced by phosphorus,
548.
Silver, soldering, 333.
Silver solutions for plating, 587, 588,
589.
Silver solution for making solid arti
cles, 607.
Silver steel, 29.
Single cell; 505.
Single cell, experiments with, 533
Single cell operations, 533.
Single pair of plates, 510.
Size of electrodes, 552.
Srnee's advice to capitalists, 554.
Smee's battery, compound, 528.
Smee's battery, how constructed, 527.
Smee's battery, modifications of, 528.
Smee's battery, properties of, 528.
Smee's claims to original discovery of
the laws of electro-deposition, 506.
INDEX.
679
Smelting, 42,
Soda, hyposulphite, preparation of, 590.
Soft soldering, 333.
Soft soldering,, examples of, 341.
Soldered joints, 332.
Solders, hard, 331, 333.
Solders, soft, 331.
Soldering, 331.
Soldering by deposition, 569.
Soldering, chemistry of, 331.
Soldering, general remarks and tabular
view, 331.
Soldering, hard, examples of, 339.
Soldering of brass, copper, lead, tin,
pewter, 331.
Soldering per se, or burning together,
334, 347.
Soldering, soft, examples of. 341.
Solid bodies, tables of the cohesive
force of, 204.
Solid silver articles, made by battery,
607.
Solutions, best sort for depositing solid
silver, 607.
Solutions, different density of, 562.
Solutions for battery, how often
changed, 537.
Solutions for deposition of alloys, 622.
Solutions of aluminium, 619,
Solutions of gold by acid, 611.
Solutions of gold by battery, 611.
Solutions of gold, preparation of, 610.
Solutions of silicum, 621.
Solutions, silver, best method of mak-
ing, 589.
Solutions, silver, for amateurs, 590.
Sources of defects in batteries, 511.
Southwark Bridge, blocks of cast-iron
in, 25.
Spades, 139.
Special metallurgic operations, 39.
Speculum metal, 334.
Spelter solder, 331, 333.
Spencer and de la Rives's failure in
. gilding, 575.
Spencer's, Jacobi's, and Jordan's
claims, 496.
Spencer's first electrotype, 501.
Spencer's first paper on electrotyping,
effects of it, when first published,
496.
Spencer, his first experiments, 493.
Spencer, his first paper upon electro-
typing, 495.
Spencer's manipulations for electro-
types, 497.
Springs and saws lose their elasticity
by grinding and polishing, 156.
Springs, hardening of, 155.
Springs, to take out of wire, 324.
Square screw-threads, 434.
Squeezers, Bessemer's, 69.
Steam-boilers, joints for, 293.
Steam-hammer, Bessemer's, modifica-
tions of, 70.
Stearine for moulds, 545.
Steel and glass, analogy between, 146,
Steel and iron, analysis of, 145.
Steel and iron, forging of, 86.
Steel, "blazing off;" 153,
Steel, blistered, 84.
Steel, cast, 84.
Steel, cementation of iron, 84.
Steel, cracking of, when suddenly
cooled, 146.
Steel, degrees of beat for, 96.
Steel, degrees of heat in working, 85.
Steel, draw-plates for wire of, 323.
Steel, encasing in-charcoal powder, 147,
Steel, fracture of, 85,
Steel, hack-hammering, 153.
Steel, hammer hardened, 85.
Steel, hammer hardening of, 145.
Steel, hard and soft conditions of, 145»
Steel, hardened tires for locomotive-
wheels, 162.
Steel, heat for tempering, 152.
Steel, manufacture of, 83.
Steel-pens, 383.
Steel-pens, heating of. 155.
Steel, practice of hardening and tem-
pering, 147.
Steel-shears, 84.
Steel, soldering, 334.
Steel, water not essential in hardening1-,
147.
Steel, whilst red-hot, in its weakest
condition, 151.
Stereotyping in copper by electrotype,
504.
Strength or cohesion of alloys, 214.
Strengths of various screws, 472.
Stripping gold from gilt articles, 614.
Stripping silver from copper, 597.
Stub gun-barrels, 135.
Sturgeon's art of electrotyping, 508.
Substitute for silver in Snaee's battery*
528.
Sulphate of copper, action upon iron,,
628.
Sulphate of copper and cyanide of
potassium mixed, 576.
Sulphate of copper, impurities, 533.
Sulphate of zinc for batteries, 536, 537
Sulphate of einc, solution for coating,
583,
Sulphides, 34,
Sulphides, reduction of, 34.
Sulphite of potash, preparation of, 591.
Sulphite of silver solution, 591.
680
INDEX.
Sulphuric acid for pickling castings,
276.
Sulphuric acid for batteries, 537
Sulphur, all metals combine with, 34.
Sulphur and phosphorus in coal-smelted
iron, 20.
Sulphur causes a low degree of fusi-
bility, 34.
Sulphur, combination of, with oxygen,
69.
Sulphur, driving off, from iron, 69.
Sulphur in iron, 71.
Sulphur in metallurgic operations, 94.
Sulphurous acid gas, formation of, 69.
Sulphurous acid, how prepared, 592.
Sulphuret of carbon, used for bright
plating, 603.
Surface joints, 272.
Suspending electrotypes, mode of, 560.
Swage bits for wire, 326.
Swage tool, 141, 287.
Swedish iron, 21, 83, 115.
Swiss drill, 393.
Szentepeteri, the Hungarian silver-
smith, alto relievo in copper, 316.
Table covers, gilt, 563.
Table of exciting solutions for batter-
ies, 537.
Table of relative intensity of batteries,
559.
Table test for free cyanide of potassium
in solutions, 602.
Taking silver from copper, 597.
Tallow, oil, wax and resin, in harden-
ing steel, 155.
Tangent screws, 427.
Tangent screw and ratchet, 461.
Taper-holes, broaches for making, 413.
Taps, cutting internal screws with, 420.
Tea-pots of sheet-metal, 310.
Teeth of saws, cutting of, 383.
Telescope-tubes, 328.
Temperature of metal for founding,
253.
Tempering and hardening, 144.
Tempering small objects in steel, 153.
Tenacity of metals, 208.
Tennant helves, 111.
Tensil strength of iron, 117.
Terrestrial globes in sheet-metal, 281.
Testing cyanide of potassium in gold
solution, 613.
Tests for cyanide of potassium, 601.
Thenard, 491.
Theoretical observations, 528.
Theory of electrolysis proposed, 631.
Thimble, gold required to gild, 617.
Thin plates of metal, flattening, with
the hammer, 316.
Threads, angular, 480.
Threads of screws, 470, 479.
Threads, square, 480.
Threads, uniform system of, 483.
Tilt-hammer, 111, 143.
Time taken by different batteries tc
deposit 1 Ib. of copper, 553.
Tin, 18, 28, 144, 179, 200.
Tin conferva^, phenomenon of, 622.
Tin, copper, zinc and lead alloys,
187.
Tin, depositing of, 619.
Tin, ductility of, 329.
Tin, gilding upon. 612.
Tin, refining of, 30.
Tin, soldering, 331.
Tin, solutions of, 622.
Tin tubes, 330.
Tinned iron, soldering, 334.
Tinned iron, wire-screws of, 419.
Tinning, 334, 347.
Tinning of metals, 217.
Tongs, crook-bit, 91.
Tongs, flat-bit, 90.
Tongs, hammer, 91.
Tongs, hoop, 91.
Top-fullers, 98.
Tools and methods for raised works in
sheet metal, peculiarities of, 313.
Tools, hardening and tempering of,
154.
Transfer engraving, Perkins's process,
159.
Transfer of elements of electrotype,
629.
Transfer of solutions, 629.
Transfer paper, preparation of, 567.
Trip-hammer, 143.
Trompe, 54.
Tubal Cain, 107.
Tubes, brass, for boilers of locomotives,
329.
Tubes, drawing metal, 327.
Tubes, tin, 330.
Tubes, welded, 136.
Turning tools, hardening of, 153.
Tutenague, 203.
Tuyeres, 94.
Tuyeres, Bessemer's, 64.
Tuyere-blocks, Bessemer's, 64.
Twisted gun-barrels, 135.
Type founding, 235.
Type founding machine, Bruce's, 236.
Type metal, 224.
Uchatius's process of refining iron, 24,
59.
Unequal action upon electrodes, 613.
Uniform cooling of forgings, necessity
of, 128.
INDEX.
631
United States, great strength of its
navy, 179.-
Uranium, 28.
Useful metals defined, 17.
Use of dipping in nitrate of mercury,
594.
Use of intensity in batteries, 558.
Use of metal moulds, 547.
Use of zinc coating for iron, 584.
Uses of observed facts, 493.
Van Mons, 491.
Vases of sheet metal, 285, 310.
Vauquelin, 491.
Veins, metallic, 501.
Vessels composed of iron plates, used
on canals, 1G7.
Voltaic pile, how constructed, 489.
Volta's discovery, 489.
Walker's manipulations, 508.
Walsh's cutter for screws, 419.
War-vessels, iron as a material for, 179.
Waste zinc, recovery of mercury from,
556.
Watch-case, gilt, how much gold re-
quired, 617.
Watch-maker's drills, hardening, 153.
Watch-springs, 156.
Water-back, 88.
Water not essential in hardening steel,
147.
AVax and rosin, 539.
Wax-moulds taken from plaster models,
543.
Wax, oil, tallow and resin in hardening
steel, 153.
Wax, to make moulds in, 539.
"Wax, to prepare for moulds, 539.
Weight, loss of, by dipping, 596.
Weight of silver deposited, how ascer-
tained, 596.
Weight of wrought-iron, steel, copper
and brass-wire and plates, 209.
Welded tubes, 136.
Welding, 105.
Welding, general examples of, 131.
Welding heat, 96.
Welding heavy works, 133.
Welding of chains, 136.
Welding of iron, 97, 121.
Welding of iron and steel, 139.
Wet process for reduction of metallic
oxides, 32.
Wheels for railways, 137.
White cast-iron, 82.
W Kite heat, 96.
White or button solders, 333.
Wind-furnaces, 44.
Wiiidow lead, 327.
Winslow's machine for compressing
and rolling puddlers' balls, 77.
Wire, annealing of, 323.
Wire for calico-printing plates, 326.
Wire, iron, coated, 579.
Wire pinion, 325.
Wires, drawing, 322.
Wood and iron for ship-building, 175.
Wollaston's and earth battery, com-
pared, 530.
Wollaston's battery, 518.
Wollaston's experiments on galvanism,
492.
Wollaston's battery, modification, 518.
Wollaston's process of hardening plates
for bank-note engraving, 161.
Woolrich's magneto-electric machino,
530.
Working drills by hand-power, 397.
Work-shop blow-pipe, 338.
Works in sheet metal made by joining,
278.
Works in sheet metal made by raising,
300.
Works published upon electro-metal-
lurgy, 508.
Works raised by the hammer, 302.
Worm-wheel cutter, 427.
Wrought and cast-iron, difference in,
21.
Wrought and cast-iron, hardening,
163.
Wrought iron almost infusible, 21.
Wrought-iron axle-trees, hardening of,
158.
Wrought-iron, change in the structure
of, during heating, 126.
Wrought-iron, chemical or molecular
difficulty in large masses, 26.
Wrought-iron, crystalline structure of,
125.
Wrought-iron, crystallizing tendency
in large masses, 26.
Wrought-iron, danger of cold hammer-
ing, 130.
Wrought-iron, Dickerson's method of
making, 75.
Wrought-iron, difficulty of welding
large masses, 26.
Wrought-iron for cannon, 117.
Wrought-iron, fusing of, for cranks,
126.
Wroiight-iron gun, bursting of, 125.
Wrought-iron gun of the Princeton,
128.
Wrought-iron guns, failure of, 129.
Wrought-iron guns, successful manu-
facture of, 129.
Wrought-iron hinges, making, 134.
Wrought-iron in large masses, 107.
682
INDEX.
Wrought-iron, internal rending or tear-
ing of, 126.
Wrought-iron ordnance, 25, 26.
Wrou ght-iron ordnance, large piece
made in Liverpool, 26.
Wrought-iron plates, effects of shot
on, 125.
Wrought-iron, practically pure iron,
21.
Wrought-iron wheels for locomotives,
137.
S"ellow brass, 188.
Yellow prussiate of potash used for
dissolving cyanide of silver, 588.
Zinc, 18, 28, 144, 179, 201.
Zinc and copper, alloys of, 183.
Zinc and copper, combination of, 225.
Zinc and copper, when melted together,
produce a high temperature, 30.
Zinc, tin, copper and lead alloys, 187.
Zinc, best sort for batteries, 511.
Zinc, deposit of, in black lead, 584.
Zinc, how often the plates should be
amalgamated, 537.
Zinc, how to amalgamate plates of,
511.
Zinc, mixing with another metal, 225.
Zinc ovens, English, 42.
Zinc, recovery of mercury from, 556.
Zinc, reduced in battery, 510.
Zinc, soldering, 333, 334.
Zinc, solution of, for coating iron, 583.
Zinc, sulphate solution of, for batteries,
537.
Zinc, use of a coating of, 583.
Zinced tin, Dr. Faraday's opinion of,
584.
Zincode, proposed term, 509.
Zincous and chlorous, 509.
INDEX TO APPENDIX.
American sheet-iron, 648.
Annealing cast-iron and cementing
steel, analogy, 652.
Blast, the, in the Bessemer process,
659, 660.
Barry, Herbert, on Russian sheet-
iron, 637.
Beardraore, Septimus, on Russian
sheet-iron, 635.
Belgian works of Seraing, classifica-
tion of steel at, 660, 661.
Belgian works of Seraing, practice of
Bessemer process at, 659.
Bessemer blowing machine, 658.
Bessemer converter, 658, 659, 600.
Bessemer steel, improvements in the
process, 657.
Blowing machine, 658.
Carbon in cast-iron, 651.
Carbon, removal of from cast-iron,
651, 652.
Carr, Crawley & Devlin's malleable
iron works, 654.
Cast-iron a compound of iron and
carbon, 651.
Castings, malleable iron, 651.
Cementing steel and annealing cast-
iron, analogy, 652.
Characteristics of Russian sheet-iron,
633.
Charcoal, strewing between the sheets
of sheet-iron, 645.
Chemical examination of Russian
sheet-iron, 633, 634.
Converter, 658, 659, 660.
Combined carbon, 651, 652.
Cost of Russian sheet-iron, 647.
Comtoise process for making Russian
sheet-iron, 635.
Cumberland pig, 657.
Decarburization of iron, 635, 652, 657,
660.
Decarburization of pig-iron for making
Russian sheet-iron, 635.
De Khanikof, N., on Russian sheet-
iron, 639.
Demidoff sheet-iron, 639.
Dinas bricks, 637.
Doctoring pig-metal, 657.
lakovleff trade mark for Russian
sheet-iron, 639.
Imitations of Russian sheet-iron, 649.
Improvements in Bessemer process,
657.
Iron, decarburization of, 652, 657, 600.
Iron, classification of, 651.
Iron for malleable castings. 652.
Iron used in Russia for sheet-iron, 641.
Kishni process, 635.
INDEX TO APPENDIX.
683
Machinery used in the manufacture of
Russian sheet-iron, 641, 642.
Malleable cast-iron, objects made of,
656.
Malleable castings, antiquity of art of
manufacturing, 653.
Malleable iron castings, 651.
Malleable iron castings, cost of, 656.
Malleable iron castings, process and
apparatus of Carr, Crawley & Dev-
lin, 664.
Malleable iron works of Carr, Crawley
& Devlin, 654.
Marshall, Phillips & Co., imitation of
Russian sheet-iron, 649.
Meshtcherin, Capt. N., on manufac-
ture of Russian sheet-iron, 641.
Michailovskoi works, 638, 639.
Objects made of malleable cast-iron,
656.
Osborn, IT. S., description of a process
for the imitation of Russian sheet-
iron, 649.
Oural mountains, production of sheet-
iron in, 640.
Oxides, use of in making malleable
castings, 652.
PastuchofFs works, 639.
Peculiarity in the method of manufac-
ture of Russian sheet-iron, 640.
Pennsylvania, manufacture of sheet-
iron in, 648.
Prerequisites for good sheet-iron, 648.
Price of Russian sheet-iron, 636.
Process and apparatus of Carr, Craw-
ley & Devlin for malleable iron cast-
ings, 654.
Process of making malleable castings,
652.
Pumpelly, Prof., on Russian sheet-
iron, 636.
Rack for hammered sheets, 646.
Reaumur on malleable castings, 653.
Reheating furnace for sheet-iron, 642,
643.
Russian Mining Journal on sheet-iron,
640.
Russian sheet-iron, causes of superior-
ity of, 636.
Russian sheet-iron, characteristics of,
633.
Russian sheet-iron, chemical examina-
tion of, 633, 634.
Russian sheet-iron, Comtoise or Kish-
ni process, 635.
Russian sheet-iron, cost of, 647.
Russian sheet-iron, descriptions of the
process of manufacture, 635, 636,
637, 639, 641, 647.
Russian sheet-iron in the Oural moun-
tains, 637.
Russian sheet-iron, imitations of, 649.
Russian sheet-iron, machinery used in
manufacture, 641, 642.
Russian sheet-iron, peculiarity in the
method of manufacture, 640.
Russian sheet-iron, price of, 636.
Russian sheet-iron, Russian Mining
Journal on, 640.
Russian sheet-iron, secrecy of process,
634.
Russian sheet-iron, uses of, 633.
Sheet-iron, American, 648.
Sheet-iron, prerequisites for good, 648.
Sheets, rack for, 646.
Spectroscope, use of in the Bessemer
process, 660.
Spiegeleisen, 657.
Steel, Bessemer, improvements in pro-
cess, 657.
Steel, classification of, at Belgian
works of Seraing, 560, 661.
Superiority of American sheet-iron,
648.
Yuicksa Works, 639.
Wood, A. & Co., imitation of Russian
sheet-iron, 649.
CATALOGUE
PRACTICAL AND
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HENRY CAREY BAIRD,
NO. 4O6 WALNUT STREET,
OF
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BOX.— A Practical Treatise on Heat:
As applied to the Useful Arts ; for the Use of Engineers, Architects-,
etc. By THOMAS Box, author of " Practical Hydraulics." Illustrated
by 14 plates containing 114 figures. 12mo ..... $4.25
BOX.— Practical Hydraulics :
A Series of Rules and Tables for the use of Engineers etc. By
THOMAS Box. 12mo ........ ' $2.50
BROWN".— Five Hundred and Seven Mechanical
Movements :
Embracing all those which are most important in Dynamics, Hydrau-
lics, Hydrostatics, Pneumatics, Steam Engines, Mill and other Gear-
ing, Presses, Horology, and Miscellaneous Machinery ; and including
many movements never before published, and several of which have
only recently come into use. By HENRY T. BROWN, Editor of the
" American Artisan." In one volume, 12mo, . . . $1.00
HENRY CAREY BAIRD'S CATALOGUE. 5
BUCKMASTER.— The Elements of Mechanical Phy-
sics :
By J. C. BUCKMASTEE, late Student in the Government School of
Mines ; Certified Teacher of Science by the Department of Science
and Art ; Examiner in Chemistry and Physics in the Royal College
of Preceptors ; and late Lecturer in Chemistry and Physics of the
Royal Polytechnic Institute. Illustrated with numerous engravings.
In one volume, 12mo $1.50
BULLOCK.— The American Cottage Builder :
A Series of Designs, Plans, and Specifications, from $200 to $20,000,
for Homes for the People; together with Warming, Ventilation,
Drainage, Painting, and Landscape Gardening. By JOHN BULLOCK,
Architect, Civil Engineer, Mechanician, and Editor of " The Rudi-
ments of Architecture and Building," etc., etc. Illustrated by 75 en-
gravings. In one volume, 8vo $3.50
BULLOCK. — The Rudiments of Architecture and
Building :
For the use of Architects, Builders, Draughtsmen, Machinists, Engi-
neers, and Mechanics. Edited by JOHN BULLOCK, author of " The
American Cottage Builder." Illustrated by 250 engravings. In one
volume, 8vo $3.50
BURGH.— Practical Illustrations of Land and Marine
Engines :
Showing in detail the Modern Improvements of High and Low Pres-
sure, Surface Condensation, and Super-heating, together with Land
and Marine Boilers. By N. P. BURGH, Engineer. Illustrated by
20 plates, double elephant folio, with text . . . . $21.00
BURGH.— Practical Rules for the Proportions of Mo-
dern Engines and Boilers for Land and Marine
Purposes.
By N. P. BURGH, Engineer. 12mo $1.50
BURGH.— The Slide- Valve Practically Considered.
By N. P. BURGH, Engineer. Completely illustrated. 12mo. $2.00
BYLES.— Sophisms-of Free Trade and Popular Politi-
cal Economy Examined.
By a BARRISTER (Sir JOHN BARNARD BYLES, Judge of Common
Pleas). First American from the Ninth English Edition, as published
by the Manchester Reciprocity Association. In one volume, 12mo.
Paper, 75 cts. Cloth $1.25
BYRN.— The Complete Practical Brewer :
Or Plain, Accurate, and Thorough Instructions in the Art of Brewing
Beer, Ale, Porter, including the Process of making Bavarian Beer,
all the Small Beers, such as Root-beer, Ginger-pop, Sarsaparilla-
beer, Mead, Spruce Beer, etc., etc. Adapted to the use of Public
Brewers and Private Families. By M. LA FAYETTE BYRN, M. D.
With illustrations. 12mo $1.25
6 HENRY CAREY BAIRD'S CATALOGUE.
BYRN.— The Complete Practical Distiller :
Comprising the most perfect and exact Theoretical and Practical De-
scription of the Art of Distillation and Rectification ; including all of
the most recent improvements in distilling apparatus; instructions
for preparing spirits from the numerous vegetables, fruits, etc. ; direc-
tions for the distillation and preparation of all kinds of brandies and
other spirits, spirituous and other compounds, etc., etc. By M. LA
FAYETTE BYRN, M. D. Eighth Edition. To which are added, Prac-
tical Directions for Distilling, from the French of Th. Fling, Brewer
and Distiller. 12mo $1.50
BYRNE.— Handbook for the Artisan, Mechanic, and
Engineer :
Comprising the Grinding and Sharpening of Cutting Tools, Abrasive
Processes, Lapidary Work, Gem and Glass Engraving, Varnishing
and Lackering, Apparatus, Materials and Processes for Grinding and
Polishing, etc. By OLIVER BYRNE. Illustrated by 185 wood en-
gravings. In one volume, 8vo $5.00
BYRNE.— Pocket Book for Railroad and Civil Engi-
neers :
Containing New, Exact, and Concise Methods for Laying out Rail-
road Curves, Switches, Frog Angles, and Crossings; the Staking
out of work ; Levelling ; the Calculation of Cuttings ; Embankments ;
Earth-work, etc. By OLIVER BYRNE. 18mo., full bound, pocket-
book form $1.75
BYRNE.— The Practical Model Calculator:
For the Engineer, Mechanic, Manufacturer of Engine Work, Naval
Architect, Miner, and Millwright. By OLIVER BYRNE. 1 volume,
8vo., nearly 600 pages $4.50
BYRNE.— The Practical Metal- Worker's Assistant:
Comprising Metallurgic Chemistry ; the Arts of Working all Metals
and Alloys ; Forging of Iron and Steel ; Hardening and Tempering ;
Melting and Mixing; Casting and Founding; Works in Sheet Metal;
The Processes Dependent on the Ductility of the Metals ; Soldering ;
and the most Improved Processes and Tools employed by Metal-
workers. With the Application of the Art of Electro-Metallurgy to
Manufacturing Processes ; collected from Original Sources, and from
the Works of Holtzapffel, Bergeron, Leupold, Plumier, Napier,
Scoffern, Clay, Fairbairn, and others. By OLIVER BYRNE. A new,
revised, and improved edition, to which is added An Appendix, con-
taining THE MANUFACTURE OF RUSSIAN SHEET-IRON. By JOHN
PERCY, M. D., F.R.S. THE MANUFACTURE OF MALLEABLE IRON
CASTINGS, and IMPROVEMENTS IN BESSEMER STEEL. By A. A.
FESQUET, Chemist and Engineer. With over 600 Engravings, illus-
trating every Branch of the Subject. 8vo $7.00
Cabinet Maker's Album of Furniture :
Comprising a Collection of Designs for Furniture. Illustrated by 48
Large and Beautifully Engraved
Plates. In one vol., oblong
HENEY CAKEY BAIRD'S CATALOGUE. 7
CALLINGHAM.— Sign Writing and Glass Emboss-
ing:
A Complete Practical Illustrated Manual of the Art. By JAMES
CALLINGHAM. In one volume, 12mo $1.50
CAMPIN.— A Practical Treatise on Mechanical Engi-
neering :
Comprising Metallurgy, Moulding, Casting, Forging, Tools, Work-
shop Machinery, Mechanical Manipulation, Manufacture of Steam-
engines, etc., etc. With an Appendix on the Analysis of Iron and
Iron Ores. By FRANCIS CAMPIN, C. E. To which are added, Obser-
vations on the Construction of Steam Boilers, and Remarks upon
Furnaces used for Smoke Prevention ; with a Chapter on Explosions.
By R. Armstrong, C. E., and John Bourne. Rules for Calculating
the Change Wheels for Screws on a Turning Lathe, and for a Wheel-
cutting Machine. By J. LA NlCCA. Management of Steel, Includ-
ing Forging, Hardening, Tempering, Annealing, Shrinking, and Ex-
pansion. And the Case-hardening of Iron. By G. EDE. 8vo. Illus-
trated with 29 plates and 100 wood engravings . . . $6.00
CAMPIN.— The Practice of Hand-Turning in Wood,
Ivory, Shell, etc. :
With Instructions for Turning such works in Metal as may be re-
quired in the Practice of Turning Wood, Ivory, etc. Also, an Appen-
dix on Ornamental Turning. By FRANCIS CAMPIN ; with Numerous
Illustrations. 12mo., cloth $3.00
CAREY.— The Works of Henry C. Carey :
FINANCIAL CRISES, their Causes and Effects. 8vo. paper . 25
HARMONY OF INTERESTS: Agricultural, Manufacturing, and
Commercial. 8vo., cloth $1.50
MANUAL OF SOCIAL SCIENCE. Condensed from Carey's " Prin-
ciples of Social Science." By KATE McKEAN. 1 vol. 12mo. $2.25
MISCELLANEOUS WORKS : comprising " Harmony of Interests,"
" Money," " Letters to the President," " Financial Crises," " The
Way to Outdo England Without Fighting Her," "Resources of
the Union," "The Public Debt," "Contraction or Expansion?"
" Review of the Decade 1857-'67," " Reconstruction," etc., etc.
Two vols., 8vo., cloth $10.00
PAST, PRESENT, AND FUTURE. 8vo $2.50
PRINCIPLES OF SOCIAL SCIENCE. 3 vols., 8vo., cloth $10.00
THE SLAVE-TRADE, DOMESTIC AND FOREIGN ; Why it Ex-
ists, and How it may be Extinguished (1853). 8vo., cloth . $2.00
LETTERS ON INTERNATIONAL COPYRIGHT (1867) . 50
THE UNITY OF LAW : As Exhibited in the Relations of Physical,
Social, Mental, and Moral Science (1872). In one volume, 8vo.,
pp. xxiii., 433. Cloth $3.50
CHAPMAN.— A Treatise on Eopemaking:
As Practised in private and public Rope yards, with a Description
of the Manufacture, Rules, Tables of Weights, etc., adapted to the
Trades, Shipping, Mining, Railways, Builders, etc. By ROBERT
CHAPMAN. 24mo $1.50
8 HENEY CAREY BAIRD'S CATALOGUE.
COLBURN.— The Locomotive Engine :
Including a Description of its Structure, Rules for Estimating its Capa-
bilities, and Practical Observations on its Construction and Manage-
ment. By ZEKAH COLBUKN. Illustrated. A new edition, 12mo. £1.25
CRAIK. — The Practical American Millwright and
Miller.
By DAVID CRAIK, Millwright. Illustrated by numerous wood en-
gravings, and two folding plates. 8vo $5.00
DE GRAFF.— The Geometrical Stair Builders' Guide :
Being a Plain Practical System of Hand-Railing, embracing all its
necessary Details, and Geometrically Illustrated by 22 Steel Engrav-
ings ; together with the use of the most approved principles of Prac-
tical Geometry. By SIMON DE GRAFF, Architect. 4to. . §5.00
DE KONINCK.-DIETZ.-A Practical Manual of Che-
mical Analysis and Assaying :
As applied to the Manufacture of Iron from its Ores, and to Cast Iron,
Wrought Iron, and Steel, as found in Commerce. By L. L. DE KON-
INCK, Dr. Sc., and E. DIETZ, Engineer. Edited with Notes, by ROBEET
MALLET, F.R.S., F.S.G., M.I.C.E., etc. American Edition, Edited
with Notes and an Appendix on Iron Ores, by A. A. FESQUET, Chemist
and Engineer. One volume, 12mo. $2.50
DUNCAN.— Practical Surveyor's Guide:
Containing the necessary information to make any person, of common
capacity, a finished land surveyor without the aid of a teacher. By
ANDREW DUNCAN. Illustrated. 12mo., cloth. . . . $1.25
DUPLAIS.— A Treatise on the Manufacture and Dis-
tillation of Alcoholic Liquors :
Comprising Accurate and Complete Details in Regard to Alcohol from
Wine, Molasses, Beets, Grain, Rice, Potatoes, Sorghum, Asphodel,
Fruits, etc. ; with the Distillation and Rectification of Brandy, Whis-
key, Rum, Gin, Swiss. Absinthe, etc., the Preparation of Aromatic Wa-
ters, Volatile Oils or Essences, Sugars, Syrups, Aromatic Tinctures,
Liqueurs, Cordial Wines, Effervescing Wines, etc., the Aging of Brandy
and the Improvement of Spirits, with Copious Directions and Tables
for Testing and Reducing Spirituous Liquors, etc., etc. Translated
and Edited from the French of MM. DUPLAIS, Aine et Jeune. By
M. McKENNiE, M.D. To which are added the United States Internal
Revenue Regulations for the Assessment and Collection of Taxes on
Distilled Spirits. Illustrated by fourteen folding plates and several
wood engravings. 743 pp., 8vo $10.00
DUSSAUCE.— A General Treatise on the Manufacture
of Every Description of Soap :
Comprising the Chemistry of the Art, with Remarks on Alkalies, Sa-
ponifiable Fatty Bodies, the apparatus necessary in a Soap Factory,
Practical Instructions in the manufacture of the various kinds of Soap,
the assay of Soaps, etc., etc. Edited from Notes of Larme, Fontenelle,
Malapayre, Dufour, and otbers, with large and important additions by
Prof. H. DUSSAUCE, Chemist. Illustrated. In one vol., 8vo. . $10.00
HENRY CAREY BAIRD'S CATALOGUE. 9
DUSSAUCE.— A General Treatise on the Manufacture
of Vinegar :
Theoretical and Practical. Comprising the various Methods, by the
Slow and the Quick Processes, with Alcohol, Wine, Grain, Malt, Cider,
Molasses, and Beets ; as well as .the Fabrication of Wood Vinegar, etc.,
eic. By Prof. H. DUSSAUCE. In one volume, 8vo. . . $5.00
DUSSAUCE.— A New and Complete Treatise on the
Arts of Tanning, Currying, and Leather Dressing :
Comprising all the Discoveries and Improvements made in France,
Great Britain, and the United States. Edited from Notes and Docu-
ments of Messrs. Sallerou, Grouvelle, Duval, Dessables, Labarraque,
Payen, Rene, De Fontenelle, Malapeyre, etc., etc. By Prof. H. Dus-
SAUCE, Chemist, Illustrated by 212 wood engravings. 8vo, $20.00
DUSSAUCE.— A Practical Guide for the Perfumer :
Being a New Treatise on Perfumery, the most favorable to the Beauty
without being injurious to the Health, comprising a Description of the
substances used in Perfumery, the Formulae of more than 1000 Prepa-
rations, such as Cosmetics, Perfumed Oils, Tooth Powders, Waters,
Extracts, Tinctures, Infusions, Spirits, Vinaigres, Essential Oils, Pas-
tels, Creams, Soaps, and many new Hygienic Products not hitherto
described. Edited from Notes and Documents of Messrs. Debay, Lu-
nd, etc. With additions by Prof. H. DUSSAUCE, Chemist. 12mo. $3.00
DUSSAUCE.— Practical Treatise on the Fabrication
of Matches, Gun Cotton, and Fulminating Powders.
By Prof. H. DUSSAUCE. 12mo $3.00
Dyer and Color-maker's Companion:
Containing upwards of 200 Receipts for making Colors, on the most
approved principles, for all the various styles and fabrics now in exist-
ence ; with the Scouring Process, and plain Directions for Preparing,
Washing-off, and Finishing the Goods. In one vol., 12mo. . $1.25
EASTON.— A Practical Treatise on Street or Horse-
power Railways.
By ALEXANDER EASTON, C. E. Illustrated by 23 plates. 8vo.,
cloth $2.00
ELDER.— Questions of the Day:
Economic and Social. By Dr. WILLIAM ELDEE. 8vo. . $3.00
FAIRBAIRN.— The Principles of Mechanism and Ma-
chinery of Transmission :
Comprising the Principles of Mechanism, Wheels, and Pulleys,
Strength and Proportions of Shafts, Coupling of Shafts, and Engaging
and Disengaging Gear. By Sir WILLIAM FAIEBAIKN, C.E., LL.D.,
F.R.S., F.G.S. Beautifully illustrated by over 150 wood-cuts. In
one volume, 12mo $2.50
FORSYTH.— Book of Designs for Headstones, Mural,
and other Monuments :
Containing 78 Designs. By JAMES FOESYTH. With an Introduction
by CMAKLES BOUTELL, M. A. 4to., cloth $5.00
10 HENRY CAREY BAIRD>S CATALOGUE.
GIBSON.— The American Dyer:
A Practical Treatise on the Coloring of Wool, Cotton, Yarn and
Cloth, in three parts. Part First gives a descriptive account of tin*
Dye Stuffs ; if of vegetable origin, where produced, how cultivated,,
and how prepared for use; if chemical, their composition, specific
gravities, and general adaptability, how adulterated, and how to de-
tect the adulterations, etc. Part Second is devoted to the Coloring of
Wool, giving recipes for one hundred and twenty-nine different colors
or shades, and is supplied with sixty colored samples of Wool. Part
Third is devoted to the Coloring of Raw Cotton or Cotton Waste, for
mixing with Wool Colors in the Manufacture of all kinds of Fabrics,
gives recipes for thirty-eight different colors or shades, and is supplied
with twenty-four colored samples of Cotton Waste. Also, recipes for
Coloring Beavers, Doeskins, and Flannels, with remarks upon Ani-
lines, giving recipes for fifteen different colors or shades, and nine
samples of Aniline Colors that will stand both the Fulling and Scour-
ing process. Also, recipes for Aniline Colors on Cotton Thread, and
recipes for Common Colors on Cotton Yarns. Embracing in all over
two hundred recipes for Colors and Shades, and ninety -four samples:
of Colored Wool and Cotton* Waste, etc. By RICHARD H. GiBSONr
Practical Dyer and Chemist. In one volume, 8vo. . . $12.50
GILBART.— History and Principles of Banking :
A Practical Treatise. By JAMES W. GILBART, late Manager of the
London and Westminster Bank. With additions. In one volume,.
Svo., 600 pages, sheep $5.00
Gothic Album for Cabinet Makers :
Comprising a Collection of Designs for Gothic Furniture. Illustrated1
by 23 large and beautifully engraved plates. Oblong . .. $3.00
GRANT. — Beet-root Sugar and Cultivation of the
Beet.
By E. B. GRANT. 12mo . . $1.25
GREGORY.— Mathematics for Practical Men :
Adapted to the Pursuits of Surveyors, Architects, Mechanics, and
Civil Engineers. By OLINTHUS GREGORY. 8vo.,, plates,, cloth $3.00
GRISWOLD.— Railroad Engineer's Pocket Compan-
ion for the Field :
Comprising Rules for Calculating Deflection Distances and Angles,.
Tangential Distances and Angles, and all Necessary Tables for Engi-
neers ; also the art of Levelling from Preliminary Survey to the Con-
struction of Railroads, intended Expressly for the Young Engineer,
together with Numerous Valuable Rules and Examples. By W.
GRISWOLD. 12mo., tucks $1.75-
GRUNER.— Studies of Blast Furnace Phenomena.
By M. L. GRUNER, President of the General Council of Mines of
France, and lately Professor of Metallurgy at the Ecole des Mines.
Translated, with the Author's sanction, with an Appendix, by L. D. B.
Gordon, F. R. S. E., F. G. S. Illustrated. 8vo. . . . $2.50
HENRY CAEEY BAIRD'S CATALOGUE, 11
GUETTIEB.— Metallic Alloys:
Being a Practical Guide to their Chemical and Physical Properties,
their Preparation, Composition, and Uses. Translated from the
French of A. GUETTIER, Engineer and Director of Foundries, author
of " La Fouderie en France," etc., etc. By A. A. FESQUET, Chemist
and Engineer. In one volume, 12mo $3.00
HARRIS. — Gas Superintendent's Pocket Companion.
By HARRIS & BROTHER, Gas Meter Manufacturers, 1115 and 1117
Cherry Street, Philadelphia. Full bound in pocket-book form $2.00
Hats and Pelting :
A Practical Treatise on their Manufacture, By a Practical Hatter,
Illustrated by Drawings of Machinery, etc. Svo. . , . $1.25
HOFMANN.— A Practical Treatise on the Manufac-
ture of Paper in all its Branches.
By CAEL HOFMANN, Late Superintendent of paper mills in Ger-
many and the United States ; recently manager of the Public Ledger
Paper Mills, near Elkton, Md. Illustrated by 110 wood engravings,
and five large folding plates. In one volume, 4to., cloth; 398
pages ............. $15.00
HUGHES.— American Miller and Millwright's Assist-
ant,
By WM, CARTER HUGHES. A new edition. In one vol., 12mo, $1.50
HURST.— A Hand-Book for Architectural Surveyors
and others engaged in Building:
•Containing Formulae useful in Designing Builder's work, Table of
Weights, of the materials used in Building, Memoranda connected
with Builders' work, Mensuration, the Practice of Builders' Measure-
ment, Contracts of Labor, Valuation of Property, Summary of the
Practice in Dilapidation, etc., etc. By J. F. HURST, C. E, .Second
edition, pocket-book form, full bound , , . . , $2.50
JERVIS.— Railway Property :
A Treatise on the Construction and Management of Railways ; de-
signed to afford useful knowledge, in the popular style, to the holders
of this class of property ; as well as Railway Managers, Officers, and
Agents. By JOHN B. JERVIS, late Chief Engineer of the Hudson
River Railroad, Croton Aqueduct, etc. In one vol., 12mo., cloth $2.00
JOHNSTON.— Instructions for the Analysis of Soils,
Limestones, and Manures.
By J. F, W, JOHNSTON. 12mo, , 38
12 HENRY CAREY BAIRIFS CATALOGUE.
KEENE.— A Hand-Book of Practical Gauging :
For the Use of Beginners, to which is added, A Chapter on Distilla-
tion, describing the process in operation at the Custom House ibi-
ascertaining the strength of wines. By JAMES B. KEENE, of H. M.
Customs. 8vo. $1.25
KEIiLEY. — Speeches, Addresses, and Letters on In-
dustrial and Financial Questions.
By Hon. WILLIAM D. KELLEY, M. C. In one volume, 544 pages,
8vo $3.00
KENTISH.— A Treatise on a Box of Instruments,
And the Slide Rule ; with the Theory of Trigonometry and Loga-
rithms, including Practical Geometry, Surveying, Measuring of Tim-
ber, Cask and Malt Gauging, Heights, and Distances. By THOMAS.
KENTISH. In one volume. 12mo $1.25
KOBELL.— EKNX— Mineralogy Simplified :
A short Method of Determining and Classifying Minerals, by means
of simple Chemical Experiments in the Wet Way. Translated from
the last German Edition of F. VON KOBELL, with an Introduction to
Blow-pipe Analysis and other additions. By HENEI ERNI, M. D.,
late Chief Chemist, Department of Agriculture, author of " Coal Oil
and Petroleum." In one volume, 12mo $2,50
LANDBIN.— A Treatise on Steel :
Comprising its Theory, Metallurgy, Properties, Practical Working,
and Use. By M. H. C. LANDRIN, Jr., Civil Engineer. Translated
from the French, with Notes, by A. A. FESQUET, Chemist and Engi-
neer. With an Appendix on the Bessemer and the Martin Processes
for Manufacturing. Steel, from the Report of Abram S. Hewitt, United
States- Commissioner to the Universal Exposition, Paris, 1867. In one
volume, 12mo. ( $3.00
LABKIN.— The Practical Brass and Iron Founder's
Guide :
A Concise Treatise on Brass Founding, Moulding, the Metals and their
Alloys, etc. : to which are added Recent Improvements in the Manu-
facture of Iron, Steel by the Bessemer Process, etc., etc. By JAMES
LARKIN, late Conductor of the Brass Foundry Department in Reany
Neafie & Co's. Penn Works, Philadelphia. Fifth edition, revised,
with Extensive additions. In one volume,, 12mo. . . $2.25
LEA VITT.— Facts about Peat as an Article of Fuel :
With Remarks upon its Origin and Composition, the Localities in
which it is found, the Methods- of Preparation and Manufacture, and
the various Uses to which it is applicable ; together with many other
matters of Practical and Scientific Interest. To which is added a chap-
ter on the Utilization of Coal Dust with Peat for the Production of an
Excellent Fuel at Moderate Cost, specially adapted for Steam Service.
By T. H. LEAVITT. Third edition. 12mo. . „ . $1.75
HENRY CAKEY BAIRD'S CATALOGUE. 13
LEKOUX, C.— A Practical Treatise on the Manufac-
ture of Worsteds and Carded Yarns :
Comprising Practical Mechanics, with Rules and Calculations applied
to Spinning ; Sorting, Cleaning, and Scouring Wools ; the English
and French methods of Combing, Drawing, and Spinning Worsteds
and Manufacturing Carded Yarns. Translated from the French of
CHAELES LEROUX, Mechanical Engineer, and Superintendent of a
Spinning Mill, by HoEATio PAINE, M. D., and A. A. FESQUET,
Chemist and Engineer. Illustrated by 12 large Plates. To which is
added an Appendix, containing extracts from the Reports of the Inter-
national Jury, and of the Artisans selected by the Committee appointed
by the Council of the Society of Arts, London, on Woollen and Worsted
Machinery and Fabrics, as exhibited in the Paris Universal Exposi-
tion, 1867. 8vo., cloth. . . $5.00
LESLIE (Miss).— Complete Cookery:
Directions for Cookery in its Various Branches. By MlSS LESLIE.
60th thousand. Thoroughly revised, with the addition of New Re-
ceipts. In one volume, 12mo., cloth $1.50
LESLIE (Miss).— Ladies' House Book :
A Manual of Domestic Economy. 20th revised edition. 12mo., cloth.
LESLIE (Miss).— Two Hundred Receipts in French
Cookery.
Cloth, 12mo.
LIEBER.— Assayer's Guide :
Or, Practical Directions to Assayers, Miners, and Smelters, for the
Tests and Assays, by Heat and by Wet Processes, for the Ores of all
the principal Metals, of Gold and Silver Coins and Alloys, and of
Coal, etc. By OSCAE M. LIEBEE. 12mo., cloth. . . $1.25
LOTH.— The Practical Stair Builder:
A Complete Treatise on the Art of Building Stairs and Hand-Rails,
Designed for Carpenters, Builders, and Stair-Builders. Illustrated
with Thirty Original Plates. By C. EDWAED LOTH, Professional
Stair-Builder. One large 4to. volume. .... $10.00
LOVE.— The Art of Dyeing, Cleaning, Scouring, and
Finishing, on the Most Approved English and
French Methods:
Being Practical Instructions in Dyeing Silks, Woollens, and Cottons,
Feathers, Chips, Straw, etc. Scouring and Cleaning Bed and Window
Curtains, Carpets, Rugs, etc. French and English Cleaning, any
Color or Fabric of Silk, Satin, or Damask. By THOMAS LOVE, a
Working Dyer and Scourer. Second American Edition, to which are
added General Instructions for the Use of Aniline Colors. In one
volume, 8vo., 343 pages. $5.00
14 HENRY CAREY BAIRD'S CATALOGUE.
MAIN and BROWN.— Questions on Subjects Con-
nected with the Marine Steam-Engine :
And Examination Papers ; with Hints for their Solution. By THOMAS
J. MAIN, Professor of Mathematics, Royal Naval College, and THOMAS
BROWN, Chief Engineer, R. N. 12mo., cloth. . . . $1.50
MAIN and BROWN.— The Indicator and Dynamo-
meter :
With their Practical Applications to the Steam-Engine. By THOMAS
J. MAIN, M. A. F. R., Assistant Professor Royal Naval College, Ports-
mouth, and THOMAS BROWN, Assoc. Inst. C. E., Chief Engineer, R.
N., attached to the Royal Naval College. Illustrated. From the
Fourth London Edition. 8vp. $1.50
MAIN and BROWN.— The Marine Steam-Engine.
By THOMAS J. MAIN, F. R. ; Assistant S. Mathematical Professor at
the Royal Naval College, Portsmouth, and, THOMAS BROWN, Assoe.
Inst. C. E., Chief Engineer R. N. Attached to the Royal Naval Col-
lege. Authors of " Questions connected with the Marine Steam-En-
gine," and the " Indicator and Dynamometer." With numerous Illus-
trations. In one volume, 8vo. . . . ' . . . $5.00
MARTIN.— Screw-Cutting Tables, for the Use of Me-
chanical Engineers :
Showing the Proper Arrangement of Wheels for Cutting the Threads
of Screws of any required Pitch ; with a Table for Making the Uni-
versal Gas-Pipe Thread and Taps. By W. A. MARTIN, Engineer.
8vo 50
Mechanics' (Amateur) Workshop:
A treatise containing plain and concise directions for the manipula-
tion of Wood and Metals, including Casting, Forging, Brazing, Sol-
dering, and Carpentry. By the author of the " Lathe and its Uses."
Third edition. Illustrated. 8vo. . . . . . . $3.00
MOLESWORTH.— Pocket-Book of Useful Formulae
and Memoranda for Civil and Mechanical Engi-
neers.
By GUILFORD L.. MOLESWORTH, Member of the Institution of Civil
Engineers, Chief Resident Engineer of the Ceylon Railway. Second
American, from the Tenth London Edition. In one volume, full
bound in pocket-book form $2.00
NAPIER.— A System of Chemistry Applied to Dyeing.
By JAMES NAPIER, F. C. S. A New and Thoroughly Revised Edi-
tion. Completely brought up to the present state of the Science, inclu-
ding the Chemistry of Coal Tar Colors, bv A. A. FESQUET, Chemist
and Engineer. With an Appendix on Dyeing and Calico Printing, as
shown at the Universal Exposition, Paris, 1867. Illustrated. In one
volume, 8vo., 422 pages $5.00
HENRY CAREY BAIRD'S CATALOGUE. 15
NAPIER.— Manual of Electro-Metallurgy :
Including the Application of the Art to Manufacturing Processes. By
JAMES NAPIER. Fourth American, from the Fourth London edition,
re vised and enlarged. Illustrated by engravings. In one vol., 8vo. $2.00
NASON.— Table of Reactions for Qualitative Chemical
Analysis.
By HENRY B. NASON, Professor of Chemistry in the Rensselaer Poly-
technic Institute, Troy, New York. Illustrated by Colors. . 63
NEWBERY.— Gleanings from Ornamental Art of
every style :
Drawn from Examples in the British, South Kensington, Indian,
Crystal Palace, and other Museums, the Exhibitions of 1851 and 1862,
and the best English and Foreign works. In a series of one hundred
exquisitely drawn Plates, containing many hundred examples. By
ROBERT NEWBERY. 4to $15.00
NICHOLSON.— A Manual of the Art of Bookbinding :
Containing full instructions in the different Branches of Forwarding,
Gilding, and Finishing. Also, the Art of Marbling Book-edges and
Paper. By JAMES B. NICHOLSON. Illustrated. 12mo., cloth. $2.25
NICHOLSON.-The Carpenter's New Guide:
A Complete Book of Lines for Carpenters and Joiners. By PETER
NICHOLSON. The whole carefully and thoroughly revised by H. K.
DAVIS, and containing numerous new and improved and original De-
signs for Roofs, Domes, etc. By SAMUEL SLOAN, Architect. Illus-
trated by 80 plates. 4to. $4.50
NORRIS.— A Hand-book for Locomotive Engineers
and Machinists:
Comprising the Proportions and Calculations for Constructing Loco-
motives ; Manner of Setting Valves ; Tables of Squares, Cubes, Areas,
etc., etc. By SEPTIMUS NORRIS, Civil and Mechanical Engineer.
New edition. Illustrated. 12mo., cloth $2.00
NYSTROM.— On Technological Education, and the
Construction of Ships and Screw Propellers :
For Naval and Marine Engineers. By JOHN W. NYSTROM, late Act-
ing Chief Engineer, U. S. N. Second edition, revised with additional
matter. Illustrated by seven engravings. 12mo. . . $1.50
O'NEILL.— A Dictionary of Dyeing and Calico Print-
ing:
Containing a brief account of all the Substances and Processes in use
in the Art of Dyeing and Printing Textile Fabrics ; with Practical
Receipts and Scientific Information. By CHARLES O'NEILL, Ana-
lytical Chemist ; Fellow of the Chemical Society of London ; Member
of the Literary and Philosophical Society of Manchester ; Author of
" Chemistry of Calico Printing and Dyeing." To which is added an
Essay on Coal Tar Colors and their application to Dyeing and Calico
Printing. By A. A. FESQUET, Chemist and Engineer. With an Ap-
pendix on Dyeing and Calico Printing, as shown at the Universal
Exposition, Paris, 1867. In one volume, 8vo., 491 pages. . $6.00
16 HENRY CAREY BAIRD'S CATALOGUE.
ORTON.— Underground Treasures :
How and Where to Find Them. A Key for the Ready Determination
of all the Useful Minerals within the United States. By JAMES
OETON, A. M. Illustrated, 12mo $1.50
OSBORN.— American Mines and Mining:
Theoretically and Practically Considered. By Prof. H. S. OSBOKN.
Illustrated by numerous engravings. 8vo. (In preparation.)
OSBORN.— The Metallurgy of Iron and Steel :
Theoretical and Practical in all its Branches ; with special reference
to American Materials and Processes. By II. S. OSBORN, LL. D.,
Professor of Mining and Metallurgy in Lafayette College, Easton,
Pennsylvania. Illustrated by numerous large folding plates and
wood-engravings. 8vo. $15.00
OVERMAN.— The Manufacture of Steel :
Containing the Practice and Principles of Working and Making Steel.
A Handbook for Blacksmiths and Workers in Steel and Iron, Wagon
Makers, Die Sinkers, Cutlers, and Manufacturers of Files and Hard-
ware, of Steel and Iron, and for Men of Science and Art. By FRED-
ERICK OVERMAN, Mining Engineer, Author of the " Manufacture of
Iron," etc. A new, enlarged, and revised Edition. By A. A. FESQUET,
Chemist and Engineer $1.50
OVERMAN.— The Moulder and Pounder's Pocket
Guide :
A Treatise on Moulding and Founding in Green-sand, Dry-sand, Loam,
and Cement; the Moulding of Machine Frames, Mill-gear, Hollow-
ware, Ornaments, Trinkets, Bells, and Statues ; Description of Moulds
for Iron, Bronze, Brass, and other Metals ; Plaster of Paris, Sulphur,
Wax, and other articles commonly used in Casting ; the Construction
of Melting Furnaces, the Melting and Founding of Metals ; the Com-
position of Alloys and their Nature. With an Appendix containing
Receipts for Alloys, Bronze, Varnishes and Colors for Castings ; also,
Tables on the Strength and other qualities of Cast Metals. By FRED-
ERICK OVERMAN, Mining Engineer, Author of " The Manufacture
of Iron." With 42 Illustrations. 12mo $1.50
Painter, Gilder, and Varnisher's Companion :
Containing Rules and Regulations in everything relating to the Arts
of Painting, Gilding, Varnishing, Glass-Staining, Graining, Marbling,
Sign-Writing, Gilding on Glass, and Coach Painting and Varnishing;
Tests for the Detection of Adulterations in Oils, Colors, etc. ; and a
Statement of the Diseases to which Painters are peculiarly liable, with
the Simplest and Best Remedies. Sixteenth Edition. Revised, with
an Appendix. Containing Colors and Coloring— Theoretical and
Practical. Comprising descriptions of a great variety of Additional
Pigments, their Qualities and Uses, to which are added. Dryers, and
Modes and Operations of Painting, etc. Together with Chevreul's
Principles of Harmony and Contrast of Colors. 12mo., cloth. $1.50
HENRY CAREY BAIRD'S CATALOGUE. 17
PALLETT.—- The Miller's, Millwright's, and Engineer's
Guide.
By HENRY PALLETT. Illustrated. In one volume, 12mo. $3.00
PERCY.— The Manufacture of Russian Sheet-Iron.
By JOHN PERCY, M.D., F.R.S., Lecturer on Metallurgy at the Royal
School of Mines, and to The Advanced Class of Artillery Officers at
the Royal Artillery Institution, Woolwich ; Author of " Metallurgy."
With Illustrations. 8vo., paper. ...... 50 cts.
PERKINS.— Gas and Ventilation.
Practical Treatise on Gas and Ventilation. With Special Relation to
Illuminating, Heating, and Cooking by Gas. Including Scientific
Helps to Engineer-students and others. With Illustrated Diagrams.
By E. E. PERKINS. 12mo., cloth $1.25
PERKINS and STOWE.— A New Guide to the Sheet-
iron and Boiler Plate Roller :
Containing a Series of Tables showing the Weight of Slabs and Piles
to produce Boiler Plates, and of the Weight of Piles and the Sizes of
Bars to produce Sheet-iron; the Thickness of the Bar Gauge in
decimals ; the Weight per foot, and the Thickness on the Bar or Wire
Gauge of the fractional parts of an inch ; the Weight per sheet, and
the Thickness on the Wire Gauge of Sheet-iron of various dimensions
to weigh 112 Ibs. per bundle; and the conversion of Short Weight
into Long Weight, and Long Weight into Short. Estimated and col-
lected by G. H. PERKINS and J. G. STOWE $2.50
PHILLIPS and DARLINGTON.-Records of Mining
and Metallurgy ;
Or Facts and Memoranda for the use of the Mine Agent and Smelter.
By J. ARTHUR PHILLIPS, Mining Engineer, Graduate of the Imperial
School of Mines, France, etc., and JOHN DARLINGTON. Illustrated
by numerous engravings. In one volume, 12mo. . . $2.00
PROTEAUX.— Practical Guide for the Manufacture
of Paper and Boards.
By A. PROTEATTX, Civil Engineer, and Graduate of the School of Arts
and Manufactures, and Director of Thiers' Paper Mill, Puy-de-D6me.
With additions, by L. S. LE NORMAND. Translated from the French,
with Notes, by HORATIO PAINE, A. B., M. D. To which is added a
Chapter on the Manufacture of Paper from Wood in the United
States, by HENRY T. BROWN, of the " American Artisan." Illus-
trated by six plates, containing Drawings of Raw Materials, Machi-
nery, Plans of Paper-Mills, etc., etc. 8vo $7.50
REGNAULT.— Elements of Chemistry.
By M. V. REGNAULT. Translated from the French by T. FORREST
BETTON, M. D., and edited, with Notes, by JAMES C. BOOTH, Melter
and Refiner U. S. Mint, and WM. L. FABER, Metallurgist and Mining
Engineer. Illustrated by nearly 700 wood engravings. Comprising
nearly 1500 pages. In two volumes, 8vo., cloth. . . . $7.50
IS HENRY CAREY BAIRD'S CATALOGUE.
REID.— A Practical Treatise on the Manufacture of
Portland Cement:
By HENRY REID, C. E. To which is added a Translation of M. A.
Lipowitz's Work, describing a New Method adopted in Germany for
Manufacturing that Cement, by W. F. REID. Illustrated by plau>>
and wood engravings. 8vo $6.00
RIFFAULT, VERGNAUD, and TOUSSAINT.— A
Practical Treatise on the Manufacture of Var-
nishes.
By MM. RIFFAULT, VERGNAUD, and TOUSSAINT. Revised and
Edited by M. F. MALEPEYRE and Dr. EMIL WINCKLER. Illustrated.
In one volume, 8vo. (In preparation.}
RIFFAULT, VERGNAUD, and TOUSSAINT.-A
Practical Treatise on the Manufacture of Colors
for Painting :
Containing the best Formulae and the Processes the Newest and in
most General Use. By M M. RIFFAULT, VERGNAUD, and TOUSSAINT.
Revised and Edited by M. F. MALEPEYRE and Dr. EMIL WINCKLER.
Translated from the French by A. A. FESQUET, Chemist and Engi-
neer. Illustrated by Engravings. In one volume, 650 pages, 8vo.
(Ready June 1, 1874.)
ROBINSON.— Explosions of Steam Boilers:
How they are Caused, and how they may be Prevented. By J. R.
ROBINSON, Steam Engineer. 12mo $1.25
ROPER.— A Catechism of High Pressure or Non-
Condensing Steam- Engines :
Including the Modelling, Constructing, Running, and Management
of Steam Engines and Steam Boilers. With Illustrations. By
STEPHEN ROPER, Engineer. Full bound tucks . . . $2.00
ROSELEUR. — Galvanoplastic Manipulations :
A Practical Guide for the Gold and Silver Electro-plater and the
Galvanoplastic Operator. Translated from the French of ALFRED
ROSELEUR, Chemist, Professor of the Galvanoplastic Art, Manufactu-
rer of Chemicals, Gold and Silver Electro-plater. By A. A. FESQUET,
Chemist and Engineer. Illustrated by over 127 Engravings on wood.
8vo., 495 pages $6.00
jp^This Treatise is the fullest and by far the best on this subject ever
published in the United States.
SCHINZ.— Researches on the Action of the Blast
Furnace.
By CHARLES SCHINZ. Translated from the German with the special
permission of the Author by WILLIAM H. MAW and MORITZ MUL-
LER. With an Appendix written by the Author expressly for this
edition. Illustrated by seven plates, containing 28 figures. In one
volume, 12mo. . $4.25
HENRY CAREY BAIRD'S CATALOGUE. 19
SHAW.— Civil Architecture :
Being a Complete Theoretical and Practical System of Building, con-
taining the Fundamental Principles of the Art. By EDWARD SHAW,
Architect. To which is added a Treatise on Gothic Architecture, etc.
By THOMAS W. SILLOWAY and GEORGE M. HARDING, Architects.
The whole illustrated by One Hundred and Two quarto plates finely
engraved on copper. Eleventh Edition, 4to., cloth. . $10.00
SHUNK.— A Practical Treatise on Railway Curves
and Location, for Young Engineers.
By WILLIAM F. SHUNZ, Civil Engineer. 12mo. , . $2.00
SLOAN.— American Houses :
A variety of Original Designs for Rural Buildings. Illustrated by 26
colored Engravings, with Descriptive References. By SAMUEL SLOAN,
Architect, author of the " Model Architect," etc., etc. 8vo. $2.50
SMEATON.— Builder's Pocket Companion :
Containing the Elements of Building, Surveying, and Architecture ;
with Practical Rules and Instructions .connected with the subject.
By A. C. SMEATON, Civil Engineer, etc. In one volume, 12mo. $1.50
SMITH.— A Manual of Political Economy.
By E. PESHINE SMITH. A new Edition, to which is added a full
Index. 12mo,, cloth $1.25
SMITH.— Parks and Pleasure Grounds :
Or Practical Notes on Country Residences, Villas, Public Parks, and
Gardens. By CHARLES H. J. SMITH, Landscape Gardener and
Garden Architect, etc., etc. 12mo, $2.25
SMITH.— The Dyer's Instructor:
Comprising Practical Instructions in the Art of Dyeing Silk, Cotton,
Wool, and Worsted, and Woollen Goods: containing nearly 800
Receipts. To which is added a Treatise on the Art of Padding ; and
the Printing of Silk Warps, Skeins, and Handkerchiefs, and the
various Mordants and Colors for the different styles of such work.
By DAVID SMITH, Pattern Dyer. 12mo., cloth. . . . $3,00
SMITH.— The Practical Dyer's Guide:
Comprising Practical Instructions in the Dyeing of Shot Cobourgs,
Silk Striped Orleans, Colored Orleans from Black Warps, Ditto from
Padding.
By DAVID SMITH. In one volume, 8vo. Price. , . $25.00
STEWART.— The American System.
Speeches on the Tariff Question, and on Internal Improvements, princi-
pally delivered in the House of Representatives of the United States.
By ANDREW STEWART, late M. C. from Pennsylvania. With a Portrait,
and a Biographical Sketch. In one volume, 8vo., 407 pages. $3.00
20 HENRY CAREY BAIRD'S CATALOGUE.
STOKES.— Cabinet-maker's and Upholsterer's Com-
panion :
Comprising the Rudiments and Principles of Cabinet-making- and Up-
holstery, with Familiar Instructions, illustrated by Examples for
attaining a Proficiency in the Art of Drawing, as applicable to Cabi-
net-work ; the Processes of Veneering, Inlaying, and Buhl-work ; the
Art of Dyeing and Staining Wood, Bone, Tortoise Shell, etc. Direc-
tions for Lackering, Japanning, and Varnishing; to make French
Polish ; to prepare the Best Glues, Cements, and Compositions, and a
number of Receipts particularly useful for workmen generally. By
J. STOKES. In one volume, 12mo. With Illustrations. . $1.25
Strength and other Properties of Metals:
Reports of Experiments on the Strength and other Properties of Metals
for Cannon. With a Description of the Machines for testing Metals,
and of the Classification of Cannon in service. By Officers of the Ord-
nance Department U. S. Army. By authority of the Secretary of War.
Illustrated by 25 large steel plates. In one volume, 4to, . $10.00
SULLIVAN.— Protection to Native Industry.
By Sir EDWARD SULLIVAN, Baronet, author of " Ten Chapters on
Social Reforms." In one volume, 8vo $1.50
Tables Showing the Weight of Bound, Square, and
Flat Bar Iron, Steel, etc.,
By Measurement. Cloth 63
TAYLOR.— Statistics of Coal :
Including Mineral Bituminous Substances employed in Arts and
Manufactures; with their Geographical, Geological, and Commercial
Distribution and Amount of Production and Consumption on the
American Continent. With Incidental Statistics of the Iroii Manu-
facture. By R. C. TAYLOR. Second edition, revised by S. S. HAL-
DEMAN. Illustrated by five Maps and many wood engravings. 8vo.,
cloth $10.00
TEMPLETON.— The Practical Examinator on Steam
and the Steam-Engine :
With Instructive References relative thereto, arranged for the Use of
Engineers, Students, and others. By WM. TEMPLETON, Engineer.
12mo $1.25
THOMAS.— The Modern Practice of Photography.
By R. W. THOMAS, F. C. S. 8vo., cloth 75
THOMSON.— Freight Charges Calculator.
By ANDREW THOMSON, Freight Agent. 24rao. . . . $1.25
TURNING: Specimens of Fancy Turning Executed
on the Hand or Foot Lathe:
With Geometric, Oval, and Eccentric Chucks, and Elliptical Cutting:
Frame. By an Amateur. Illustrated by 30 exquisite Photographs.
4to $3.00
HENRY CAREY BAIRD'S CATALOGUE. 21
Turner's (The) Companion:
Containing Instructions in Concentric, Elliptic, and Eccentric Turn-
ing : also various Plates of Chucks, Tools, and Instruments ; and Di-
rections for using the Eccentric Cutter, Drill, Vertical Cutter, and
Circular Rest ; with Patterns and Instructions for working them. A
new edition in one volume, 12mo. $1.50
URBIN.-BRULL.-A Practical Guide for Puddling
Iron and Steel.
By ED. URBIN, Engineer of Arts and Manufactures. A Prize Essay
read before the Association of Engineers, Graduate of the School of
Mines, of Liege, Belgium, at the Meeting of 1865-6. To which is added
A COMPARISON OF THE RESISTING PROPERTIES OF IRON AND STEEL.
By A. BRULL. Translated from the French by A. A. FESQUET, Che-
mist and Engineer. In one volume, 8vo $1.00
VAILE.— Galvanized Iron Cornice- Worker's Manual:
Containing Instructions in Laying out the Different Mitres, and Ma-
king Patterns for all kinds of Plain and Circular Work. Also, Tables
of Weights, Areas and Circumferences of Circles, and other Matter
calculated to Benefit the Trade. By CHARLES A. VAILE, Superin-
tendent " Richmond Cornice Works*" Richmond, Indiana. Illustra-
ted by 21 Plates. In one volume, 4to $5.00
VILLE.— The School of Chemical Manures :
Or, Elementary Principles in the Use of Fertilizing Agents. From the
French of M. GEORGE VILLE, by A. A. FESQUET, Chemist and Engi-
neer. With Illustrations. In one volume, 12 mo. . . $1.25
VOGDES.— The Architect's and Builder's Pocket Com-
panion and Price Book:
Consisting of a Short but Comprehensive Epitome of Decimals, Duo-
decimals, Geometry and Mensuration ; with Tables of U. S. Measures,
Sizes, Weights, Strengths, etc., of Iron, Wood, Stone, and various
other Materials, Quantities of Materials in Given Sizes, and Dimen-
sions of Wood, Brick, and Stone ; and a full and complete Bill of
Prices for Carpenter's Work ; also, Rules for Computing and Valuing
Brick and Brick Work, Stone Work, Painting, Plastering, etc. By
FRANK W. VOGDES, Architect. Illustrated. Full bound in pocket-
book form $2.00
Bound in cloth. 1.50
WARN.— The Sheet-Metal Worker's Instructor:
For Zinc, Sheet-Iron, Copper, and Tin-Plate Workers, etc. Contain-
ing a selection of Geometrical Problems ; also, Practical and Simple
. Rules for describing the various Patterns required in the different
branches of the above Trades. By REUBEN H. WARN, Practical Tin-
plate Worker. To which is added an Appendix, containing Instruc-
tions for Boiler Making, Mensuration of Surfaces and Solids, Rules for
Calculating the Weights of different Figures of Iron and Steel, Tables
of the Weights of Iron, Steel, etc. Illustrated by 32 Plates and 37
Wood Engravings. 8vo. . $3.00
22 HENRY CAREY BAIRD'S CATALOGUE.
WARNER.— New Theorems, Tables, and Diagrams
for the Computation of Earth- Work :
Designed for the use of Engineers in Preliminary and Final Estimates,
of Students in Engineering, and of Contractors and other non-profes-
sional Computers. In Two Parts, with an Appendix. Part I. — A
Practical Treatise ; Part II.— A Theoretical Treatise ; and the Appen-
dix. Containing Notes to the Rules and Examples of Part I. ; Expla-
nations of the Construction of Scales, Tables, and Diagrams, and a
Treatise upon Equivalent Square Bases and Equivalent Level Heights.
The whole illustrated by numerous original Engravings, comprising
Explanatory Cuts for Definitions and Problems, Stereometric Scales
and Diagrams, and a Series of Lithographic Drawings from Models,
showing all the Combinations of Solid Forms which occur in Railroad
Excavations and Embankments. By JOHN WAENEE, A. M., Mining
and Mechanical Engineer. 8vo $5.00
WATSON".— A Manual of the Hand-Lathe:
Comprising Concise Directions for working Metals of all kinds, Ivory,
Bone and Precious Woods ; Dyeing, Coloring, and French Polishing ;
Inlaying by Veneers, and various methods practised to produce Elabo-
rate work with Dispatch, and at Small Expense. By EGBERT P.
WATSON, late of " The Scientific American," Author of " The Modern
Practice of American Machinists and Engineers." Illustrated by 78
Engravings $1.50
WATSON.— The Modern Practice of American Ma-
chinists and Engineers:
Including the Construction, Application, and Use of Drills, Lathe
Tools, Cutters for Boring Cylinders, and Hollow Work Generally,
with the most Economical Speed for the same ; the Results verified by
Actual Practice at the Lathe, the Vice, and on the Floor. Together
with Workshop Management, Economy of Manufacture, the Steam-
Engine, Boilers, Gears, Belting, etc., etc. By EGBERT P. WATSON,
late of the " Scientific American." Illustrated by 86 Engravings. In
one volume, 12mo $2.50
WATSON.— The Theory and Practice of the Art of
Weaving by Hand and Power :
With Calculations and Tables for the use of those connected with the
Trade. By JOHN WATSON, Manufacturer and Practical Machine
Maker. Illustrated by large Drawings of the best Power Looms.
8vo $10.00
WEATHERLY.— Treatise on the Art of Boiling Su-
gar, Crystallizing, Lozenge-making, Comfits, Gum
Goods.
12mo $2.00
WEDDING.— The Metallurgy of Iron;
Theoretically and Practically Considered. By Dr. HERMANN WED-
DING, Professor of the Metallurgy of Iron at the Royal Mining
Academy, Berlin. Translated by JULIUS Du MONT, Bethlehem, Pa.
Illustrated by 207 Engravings on Wood, and three Plates. In one
volume, 8vo. (In press.)
HENRY CAREY BAIRD'S CATALOGUE. 23
WILL.— Tables for Qualitative Chemical Analysis.
By Professor HEINBICH WILL, of Giessen, Germany. Seventh edi-
tion. Translated by CHARLES F. HIMES, Ph. D., Professor of Natu-
ral Science, Dickinson College, Carlisle, Pa.
WILLIAMS.— On Heat and Steam :
Embracing New Views of Vaporization, Condensation, and Explosions.
By CHARLES WYE WILLIAMS, A. I. C. E. Illustrated. 8vo. $3.50
WOHLEB.— A Hand-Book of Mineral Analysis.
By F. WOHLER, Professor of Chemistry in the University of Gottin-
gen. Edited by HENRY B. NASON, Professor of Chemistry in the
Rensselaer Polytechnic Institute, Troy, New York. Illustrated. In
one volume, 12mo $3.00
WORSSAM.— On Mechanical Saws:
From the Transactions of the Society of Engineers, 1869. By S. W.
WORSSAM, Jr. Illustrated by 18 large plates. 8vo. . . $5.00
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